I wouldn't support fines based on income for all violations but I believe some might be warranted. Take speeding for an example. A poor person could have half to their entire paycheck for a week nullified due to going 1-4 mph over the speed limit (least expensive speeding ticket in USA) while it wouldn't affect a rich person at all. My sister's husband is one of these semi "rich" people that doesn't give a fuck (he probably gets at least 3 each year). The fine is more likely to change a poor person's driving habits.
Well back to my Australia example, it is not so much that there is more poor people but they are just down right irresponsible (not all, but the ones I call bogans, is a subset of poor class).
Here we have Demerit points (not sure if each state varies). If you loose all your points within like a 3 year period you loose your license. What people use to do is find a buddy in the northern territory (NT) and get them to claim they were the one driving, as their state did not have Demerit points. So you could keep on getting fined and you would never loose points. Now NT has points so that loophole was closed.
Back to the bogans, they honestly do not give a fuck. They keep reoffending and continue driving unlicensed and don't pay their tickets. The worst offenders do eventual end up in commuity service or jail if they get caught on a regular basis.
To combat this some states have introduced hoon laws (basically being morons on the road), where depending on what you are doing, you can get your car inpounded by the police for 3months to 12months. Eventually if you get caught enough times they will crush your car.
Rich people on the other hand do care as they need transport to get to work, so they don't want to loose their license.
I guess the outcome of this is, it all depends on your countries laws and culture on who cares and doesn't. So to answer your question it may be possible to deter rich people with higher fines in some countries that dont have license suspensions.