The cost of risk externalized by one person speeding is about the same, modulo driver skill and location and whatnot; it is not very sensitive to rich the driver is. If the goal of the law is to impose enough additional risk of a fine to compensate for the externalized risk, then it makes perfect sense that millionaires don't need to obey speed limits--as long as they can pay up.
If the law is intended as a deterrent, this obviously isn't working.
Bean counters will manage it though, if asked.
And this is sensible. How do you compensate a family for a dead body? You can't. So the purpose of the law should be to prevent the need for that compensation in the first place.
Treating people differently through some arbitrary definition of difference is wrong. Either we're all equal in front of the law or some animals are more equal than others. And the kind of justice you're peddling is what has set countries across the world on fire recently; the uneven application of the law.
[Edit] I don't think I was clear. Everywhere we see special cutouts in the law, all that happens is that the more capable less scrupulous people capture those cutouts. The best we can hope to do is to treat everyone exactly the same in front of the law.
"Equal in front of the law" actually means that financial penalties should be progressive in the same way taxes should be. Some countries actually do this, and they're not on fire.
How would it not be treating "everyone exactly the same in front of the law" to just say that fines are assessed as a percentage of income and/or net worth?
All of that said, personally I wouldn't extend this all the way back to the original argument about theft though, stealing $1000 is the same regardless who you steal it from, at least as far as the law should be concerned. I could see a moral difference, but the law often does not (and can not) make moral distinctions. It could however make reasonable distinctions in the application of the punitive aspects, as it sometimes does in terms of jail sentencing.