Do you really think that $200 fine has the same meaning for a elderly person on Social Security that it has for Bill Gates? Paying the percentage of income will hurt equally.
Of course not. Is the role of law enforcement to equalize "pain," or to discourage unacceptable behavior? No matter the size of the fine levied on the "evil rich guy," it won't get his attention as much as a suspension or revocation of the applicable license or permit. That's closer to equality.
This is a slippery slope. Would you really advocate the government determining how much you could "afford"? To me, the implications are scary.
Worry about yourself. A system to vary my punishment for a driving offense based upon how well my business did last year is insane. Makes all the sense of beating your kids according to the weather. I don't care if it'll gouge people richer than me even worse, all I need to know is that it's capricious to me. Nuts to that.
Ideology aside, in practical terms traffic tickets are already at least as much about revenue as they are about safety. If pulling over the well-to-do is made a multi thousand dollar jackpot, every cash strapped municipality will give their cops a Beemer quota and it will no longer be possible to drive while affluent. Hire a chauffeur.