In my baseless opinion, the "shame on you" radar signs are probably pretty effective. And definitely preferable to robot overlords handing out tickets. And doubly less offensive than charging people more based on income. At least here in the US, we have the concept that all citizens are treated equally in the eyes of the law. I don't want a system that intentionally punishes rich|poor|black|white|smart|dumb people more than any other.
Also, what if someone's wealth changes between the ticket and the penalty? If they are rich when given the ticket, but lose it all, is it still fair to charge them the higher rate?
My point is: changing from an absolute value to a relative one introduces complexities in the system. Philosophically, the law needs to treat everyone the same, which to me, means the penalties are the same for everyone regardless of sex, race, income, height, weight, or any other characteristic. This is encoded in the Constitution. I do not see how two different people, convicted of the same crime in the same contexts, should have different punishments. (Yes, I know it happens, but I think that's a bug, not a feature, and wish it would be cleaned up.)
Should we also do prison sentences based on life expectancy?
Suppose the penalty for murder is 50% of your remaining life. Should we put a 20 year old away until he's 50 (assuming 80 years expected lifespan), but only lock a 60 year old up for 10 years?