Whoa, slow down. This doesn't change -anything- about current traffic ordinances, nor what happens to repeat offenders. None of your scenarios will play out in any way differently. There's no slippery slope. It simply scales -penalties-, not the definitions of the violations, in a more rational and effective way. Which can only increases deterrence on -all- potential violators, which would increase public safety as some won't treat a too low fine as a slap on the wrist to be ignored. 

And this needn't lower current fines at all, nor "soak the rich." As an example, a $200 fine, which is in the current red light range, is just 0.8% of an income of $25,000. Apply that to someone with -twice- the income and it's still only $400 for the same offense, only a bit higher than now.

As far as Constitutionality, the penalty is -exactly- proportional regardless of who the offender is. If anything it eliminates the current disparity of impact arguments some might make. Which is the whole point.