Can you see a particularly cash-strapped town telling officers to skip the Toyota Camrys and instead pull over the BMWs? It seems ideal for abuse, selective law enforcement, and likely other bad behaviors.
Oddly enough, this would likely go away with self-driving cars as high income people switch to vehicles who "can't" break the law.
I mean, obviously a completely different scenario, but, how many times have revolutions killed all the rich/powerful people? They don't have infinite protection just cause they're rich.
If we're reaching the point where we're discussing about revolutions and civil forfeiture, I think there's a bigger problem here. And it's not proportional fines.
One is proportional and happens on conviction while the other can be nuts.
No I see a world where neither Toyotas nor BMWs are speeding. But if both are speeding, then owners of both should feel equal amount of pain. And equal amount of pain won't come from equal amount absolute fines (300$ is a drop in the bucket for a billionaire, significant for a poor person).