A bit late to this, but here we go.
TL;DR: Politics. What was intended as a test program for a few thousands gets unexpectedly popular. By the time politics align to get rid of it, it is to popular to touch, and much to expensive to expand.
So there is a report, based on lots of research, that getting an animal between the age of 35 and 55 is very beneficial to the individual, and therefore to society. [Note: this may even be true. There may even have been one!] It makes the caretaker move more! You meet new people and make new friends at an age where that is not so easy. If you have children it is good for both their health and their development. The list goes on - there are lots of benefits! Few disadvantages! Clearly the government should be supportive of middle aged people getting an animal. And in principle that is something everyone can get behind. But exactly how? And so we get to politics...
It's complicated - and expensive
There is this faction that thinks getting an animal should not be dependent on the person’s income. Why should only rich people get a better life!? The government should pay the full cost of having an animal! There is this other faction that thinks that a small tax break for all would be best. Some think all animals and pets should be allowed, others want only animals with a scientifically proven effect over a certain threshold to be included. (There is no agreement in the later group on how high that threshold should be.) What should the lower and upper limits on age be? How about married people - should they get support while either is in the supported age interval? Or do both need to be inside? What about people that already have pets when they reach the lower age limit- should they be supported? Or are only people getting an animal covered? Actual policy is hard! The list of things that needs to be resolved is long! And we are not even at the big thing: COST.
Because any sort of support will cost money. And that money will be need to be found. Supporting all pets from 35 to 55, even with a modest amount, would cost more than the government spends on infrastructure and housing combined. So that is out. In fact cats and dogs are not possible either - there is just too many, finding that sort of money is not possible. Not to mention horses - lots of them around, and very expensive.
But money can be found for something ...
In the end a compromise is found. Any citizen will receive support for a Llama while they are 44 years of age. Llamas was one of the animals with the best effect. (This is later shown to be a statistical artifact, but by then it does not matter.) More importantly there are not that many around, so it will not cost that much regardless of how many would like one. And while no-one says this, a Llama is not the most convenient animal to have, so this should keep signup low. And the costs covered are stingy, so it should not be possible to make much of a profit to provide Llamas, preventing Llama speculation!
So the law goes into effect. It is marketed as a trial - if it is successful it will be expanded, if not it will be canceled. But due to some arcane budget resolution rules and the way it was bundled with other stuff in the budget it was passed as a benefit that the government needs to cover regardless of cost. No-one cares much about this at the time. “Llamas at 44” is a small sum compared to other stuff and projected to stay that way.
... which turns out to be unexpectedly popular.
But once the law goes into effect it turns out to be fairly popular. Not wildly, that will come later. But more popular than expected. And Llama breeders all over the world suddenly see an opportunity, and avert the expected Llama shortage. It also turns out that renting/leasing people their 1-year Llama is - as designed! - a lousy business, lots of people are generous with the Llama provider, in particular when delivering the animal back (Would you like to give your Llama a three-month free range mountain vacation before the next person takes over? Of course you would, if you can afford it!), so there are some money to be made after all. (Unexpected tax-avoidance thing having to do with how Llama refund is structured is also promising in explaining how the Llama provider business took of much more than expected.)
This concerns some people, but none of those who voted for it wants to reverse course so soon and seem a flip-flopper. Much better to wait a bit until the initial enthusiasm have died down and scale the program back. And some of those very much against it, now sees that some government-supported Llama jobs will not hurt their chance of reelection. And honestly, while it is now projected to be more expensive than initially, it is still pocket change. Why create lots of trouble for yourself now, when it is likely that once someone have been killed by their Llama the voters will be in favour of removing the program? Finally there are much more important battles to fight than Llamas. Llamas can wait.
And so one year of Llama program turns into two, and three and four. By now it is really getting popular and costing LOTS of money. But gridlock means that the votes to change it cannot be found. Perhaps a compromise could be found, but the no-Llama faction shows no interest in a compromise with the less-(expensive)-Llama faction. Without that the program continues unchanged.
Why it is not removed
So it takes 13 years from the first Llama was handed out before no-Llama has control of the government. “Less waste” have been their election slogan, and while no-one said that Llamas needed to go - indeed many of them promised the opposite - they now make clear that the government have no role in Lllama-support and it will be canceling the program ASAP.
But it turns out the program is very popular. There is the 9 year old that comes to a town hall meeting and begs her representative to vote no. They were getting a Llama next year and without government support they cannot afford it. It is so genuine and precious; it is the viral sensation of the week. There are a surprisingly large number of men in their early forties that are enraged that their supported Llama will be taken away. Variations of “I paid for all those Llamas - I want mine!” are heard by phone operators for no-Llama representatives all over the country. Children and young adults have been looking forward to their Llama. Grandparents thinks it is idyllic that their grandchildren can have one. Polls indicate that women in particular thinks Llamas make the country more real, more like it should be. Whatever that means, making the country less like it should be does not seem like a winning reelection strategy.
And the Llama Association (aka BigLlama) have been fearing this since it was started. If Llama support is withdrawn an enormous amount of jobs will be lost (all of that money is after all going somewhere) they warn. There are more jobs in Llama than the automotive industry! More than half of all Llamas would need to be put down in the first year! They have been collecting the mailing addresses of Llama loaners for years and sending out a personal card with a picture of the Llama they had most recently. Now they send out an extra card with “This may be my last card, representative N N does not think anyone new should get to love me”. Even if polling shows many agree in principle that Llamas are a bit of waste, it takes a principled person to support no-Llama when the Llama your father had when you were 12 is about to become sausage.
So getting rid of Llama support is no longer on the agenda. For a while Llama reform is being discussed. Trimming the program in a way that saves real money without being really impopular is not possible. Including cheaper animals like dogs are discussed, but modelling shows that lots of people would still get a Llama, while additional people would get a dog, so that it may end up more expensive! Also BigLlama is very much opposed, and it would shift money from rural Llama jobs to dog owners which is not an election winning strategy for the no-Llama faction.
And why it is not expanded
A few years later a Llama friendly government takes power. It considers expanding the program. Perhaps 44 and 45 year olds? But it would be very expensive, and most people that have a Llama seem happy with the one year limit. Sad to give their Llama up yes, but also glad that their Llama year is up. Expanding to more animals are considered, but are rejected for much of the same reason that no-Llama did. Letting people select a year between 40 and 50 to have their Llama is trialed in certain areas. But it turns out that makes many fret over if and when to have their Llama, rather than being excited or not for their 44th birthday. Changing the age to 42 is discussed, but it would create chaos in the Llama industry during the transition, and some would be upset since “42 is not the right age to have a Llama” as one voter stated when this came up.
Lots of small things are changed. But nothing major. Which means we are where we started: The year you are 44 the government will support your Llama.
Note: Having written this, I realize that it has similarities to what is going on just now regarding health care in the US. This is mostly incidental, as this sort of process is more-or-less builtin to any new entitlement. I have opinions on the government’s role in providing health-care, but I don’t mean to express them by this piece of writing, and don’t think I do.