> care about $100

He will care if he loses his driver's license after a certain number of tickets, though, which is the law for everybody, equally applied.

In reality, even that isn't equal. A poor person who has moved out of the city because they can't afford housing inside of it losing their license would probably mean losing their job, as public transportation options may not even be available. A wealthy person could just hire an Uber everywhere and wouldn't even notice the cost.

While the punishment is equal, the impact it would have on different populations is unequal (which is the same issue with a fine of an absolute amount).