Desertion is a function of population counts dropping to zero, and is completely unregulated (with some exceptions).
Believe it or not, we actually have 'ghost towns' in Australia as well, despite the country being relatively young in terms of European construction. The principal reason that towns empty or that houses are left abandoned is economic failure.
If we look at the city scale first, then abandonment isn't that hard to understand. All communities need some form of industry to survive; something that employs people to generate production of a good or a service.
In some places, that's agriculture (food and textiles). In others, it's mining. In still others, it's tourism. In short, towns need something that gets people to spend money on what they produce.
So; what generates ghost towns in Australia? Mines dry up, rest stops like service stations and pubs get bypassed by big highways, etc. Certainly there are a number of points in Australia that Cobb & Co (Australia's implementation of stage coaches) would have stopped that cars can simply drive past before needing fuel, meaning that there's no economic value to the location anymore, and people leave. Once you fall below a certain critical mass of population, it's not worth the supporting businesses like grocers or petrol stations to remain, and the town dies.
In the case of individual homes being abandoned, the principle is the same only on a smaller scale. Some people can go into town only to find that the bank is foreclosing on their mortgage, and they just up and abandon the place. People living somewhere can die, and either there are no clear heirs so it goes into probate, or the heirs don't want the property and can't find buyers. In either case, the property can easily fall into sudden disrepair, especially if it wasn't being actively maintained in the first place.
The economic aspect of this also explains why this goes unregulated, and why there aren't government groups that preserve or maintain such sites - if people are leaving because of local economic collapse, there's no benefit to the government to maintain these buildings because their resources would be better spent in locations where there is new industry attracting those people. In other words, government should be investing public money in places where people are, not places they aren't.
There is a single exception to this, and that's where the site has some form of historical significance. This happens a lot in Europe, but even the USA and Australia have such agencies to preserve sites of historical significance.
The problem is, the budgets are tight and the cost of maintaining these sites can be huge. Good construction is not a panacea for lower maintenance costs over time. If it was, then cathedrals wouldn't have such huge maintenance costs associated with them. So, often these agencies have to pick and choose what they spend money on.
When you get right down to it, buildings not only have a large initial construction cost, but they have a large regular maintenance cost associated with them as well. Owning a house is great, but unlike renting, you're personally responsible for keeping it in good repair, and that can be tough if you don't have a lot of money coming in. The initial cost of the properties may lead people to think that abandonment rates should drop, but then the cost of maintenance can be a good reason for people walking away from them, especially if the owner has a mortgage on the property for around 100% of the price of it; in other words, has no skin in the game.
As such, the real question is whether or not any of these buildings can be recycled. Venezuela had a case of that very thing happening, with a building that was called the Tower of David. I believe the squatters there have been moved on now, but it does go to show that in an environment where resources are limited, even abandoned projects can find new purpose.