In the UK, speeding fines are also backed by "points" added to your license - get enough of them and you lose your license altogether for a while. It's similar in at least some other European countries.

That is a definite punishment for anyone that cares enough about driving that they were doing it in the first place, while also clearly not being revenue generating (in fact it prevents future fine revenue). I'm not sure that would wash in the car-centric States though (but it would make it an even juicier punishment). But since you don't get banned immediately, it's potentially low-impact on a per-ticket basis.