Camera-based traffic enforcement is sort of the opposite of market forces,
Whilst it's not market based, its not the opposite.
I'd hate to think how bad market based enforcement would be, not only would they be required to make a profit, they'd be required to charge us as much as they could get away with as often as possible. Here in the UK you can get a maximum of 4 speeding fines over a 3 year period before its a holiday off the road, they are also pretty lenient with the speeding fines too compared to Australia (I.E. doing 55 in a 50 zone wont get you nicked, even 60 would be ignored by a copper, perhaps not an average speed camera).
Its almost as if they don't want to fine you, especially how clearly speed cameras are marked.
A market based approach would get rid of the endorsement/demerit point system because a customer off the road is a customer that cant rack up new fines. They would also put hidden speed cameras everywhere, camouflaged and make appealing a fine so painful that it's impossible. They would also make it low enough that you'd pay the fine rather than fight it... Much like they do with parking fines here in the UK (my council charges 70 quid, but reduces it to 35 if you pay within 2 weeks).
I'm not a big fan of the current enforcement system (too many people fail to indicate, tailgate, fail to keep a safe distance, don't know how to merge and other violations of the Highway Code are ignored when speeding is heavily enforced (relatively speaking)) but despite that, market based enforcement would suck a million times more.
If you need proof of this, look at market based solutions for car insurance here in the UK. Insurance is mandatory to drive on the road, so it costs an insane amount because the insurers are pretty much unregulated. For fully comprehensive insurance I went from paying in Australia A$900 (GBP 450) for a Nissan Silvia S15 (one of the most stolen cars in my state) to paying GBP 700 for a bog standard BMW Z4 3.0i that was worth about 1000 quid less in the UK.