The system right now runs on people whose job it is to care. Fundamentally day to day, they're expected to show up, read the documents, make sure everything makes sense and then take a vote on whether to go ahead with a change. Yes this is normally done from a partisan rather than impartial viewpoint, but everyone either has an agenda on an issue or is ignorant of it.
Your system is a self selecting Oligarchy/Meritocracy. It's run by the people who are either rich enough to pay someone to write the code and then publicise it enough to get it voted through, or clever enough to do all that themselves (or be a member of a special interest group with the resources to do this but we'll get to them later).
You're asking 70% (I'll look at this later) of the population to support a vote on minor details about which the vast majority of them really don't actually care. To be able to make an informed vote they'd have to spend considerable time looking into this minor change in tax law for small businesses and check that it doesn't create a gaping loophole that the multinationals can exploit. Believe it or not, that's not unreasonable. Statistically mass votes like that can average the right answer.
Split the vote into two parts, the code, and the effect. Unfortunately you're asking people to vote on two factors at once, both the quality of the code and the changes it makes. In most cases people will only care about one or other of these. The people who understand the code may not care much for what happens to the small traders, the small traders won't understand the code.
The biggest problem is participation. Around 60% of the population is registered to vote, of whom around 60% vote in national elections. (US UK about the same) So you're looking at a real turnout around 40% of the population, and that's for major elections. The elections I see day to day generally have an expected turnout in the range of 15%-25% of registered voters, and these are online votes. In an active government minor details are voted on on a steady basis. You're effectively asking a large percentage of the population to take considerable time every day to learn about and make an informed decision on complex legal/tax/political matters. Total paralysis ensues.
So we accept a smaller participation, maybe a simple majority, what of it? You now get the problem of active special interest groups. They get to mess around and get their own way just by virtue of being organised enough to do it. A little low profile mass mobilisation of the group and they're taking control of things that aren't in the best interests of the population. One of the primary jobs of a responsible democracy is to stop even a majority causing harm to a minority group.
The vote that benefits everyone? Let's all vote to not have to pay tax, I can see that passing first time. Who votes for taxes. What do you mean I can't still have my free healthcare? I'm voting for free healthcare as well. Many people don't understand that everything has to be paid for somehow, and it's much easier to get money out of the large population of honest but poor people who pay their taxes, than the small population of rich people who understand how not to pay tax.
The loaded vote. Do you want your left or right foot amputated? That's an extreme case admittedly but it's not that unusual to not want either outcome of a possible vote. A lot of people didn't want either Trump or Clinton, but you were going to get one or the other no matter what.
The nutter. Say I want to legalise the rounding up and expulsion of [insert minority group] how many times can I submit variants of this legislation to the system before one slips through unnoticed? Not enough people are voting and it passed on a simple majority. Maybe I'm a member of a special interest group who submitted a vote to replace the whole thing with a committee run by themselves. Sooner or later it'll get through, but now instead of doing constructive work, people are having to spend the evening voting out the craziest of proposals. Again paralysis.
Give people a cooling off period if they submit rubbish There are a couple of hundred (thousand) people in my organisation, someone else can submit it.
Only vetted and approved persons are allowed to submit (or vote on) proposals with a budget to get someone to write the code if needs be. Maybe, but ultimately this becomes technocracy which is possibly worse than we have right now.
A few quick and dirty definitions.
Meritocracy: Run by the best and brightest.
Technocracy: Run by the numbers.
Oligarchy: Run by the people with money.