But how, in this specific case, does larger population size impact the implementation of income-tied fines?
Edit, further specification: doesn't the US, at least on a state by state fashion, have some kind of standard declaration /way of determining your income?
But do you think this is an unbearable problem, and it will make the whole thing impractical, and the benefits are not enough?
Edit: And could have unintended consequences for the court system, and create unintended incentives to ticket higher income people more vigorously than lower income (potentially creating unenforced laws in lower income areas).
I doubt that would be the case, because wealthy people have access to better lawyers, and police know this. It's one of the reasons they're currently more likely to abuse poor people. They also know that there will be less societal outrage.
Everything has drawbacks, and I am not competent enough to estimate all possible effects on society at large. But the current system does not seem to be perfect either, and ideas for improving it should be considered (and sometimes discarded, of course).
You're only thinking of one half of the problem. The rich people who are targeted more vigorously will be able to fight back. But the poor people who are left living in communities where the laws aren't being applied will have to live with the results of lack of enforcement. It sucks living in a place where the police will not punish offenders because it's not worth the effort.