> Assuming an income distribution like what we have in reality, this means that a certain percentage of our population will have so little income that the fine will ruin their life, making them less effective and thus our population less effective. And there's no way we can remove this by adjusting the price of our constant fine. If we remove the fine, then everyone speeds. Even at the best sweet spot, we'll have a system where some people will always speed, and some people will never rationally choose to speed but will be economically "killed" by the fine anyway.
We already have a system for this, which is that the fine for speeding scales with speed. Then someone who can't afford the fine can drive more conservatively, so that if they make a mistake the degree to which they violate the rule is smaller, which reduces both the probability of enforcement and the amount of the fine.
Having at least that level of fine is inherently necessary, even for lower income people, because otherwise there is insufficient disincentive for them to speed and there is no compensation to society in the form of a proportionate fine when they do.
We can let a rich person get a thousand small speeding fines because taking their money and using it for lead abatement or cancer research saves more lives than they're risking. But we can't let anyone take that risk without "paying for it" or the net result is a very big social loss, multiplied by every person in that category who longer has any incentive not to do it.
Moreover, talking about "economic death" over a matter of something like a $250 fine is an exaggeration. Even for someone making the federal minimum wage, that's less than 2% of their income. That amount of money doesn't make the difference between whether anybody files for bankruptcy or not, it only makes the difference between whether it happens this month or next. And if you want to help those people, don't waive their traffic fines, just take all the money you would have waived in traffic fines and give it to lower income people regardless of whether or not they violated a traffic law or not -- so that you're helping them but not giving them incentive to misbehave.