> I would submit that there is the danger that people might want to keep a bad law if they continue to make money by snitching. In fact, money is the exact wrong incentive for this sort of thing.

Think bigger. If the activity were really a money-maker, then it will inevitably be scaled and industrialized. A cottage industry of snitching would spring up. If that industry got sufficiently wealthy and politically powerful, we'd see all kinds of "easy-bounty" laws getting enacted to allow these companies to further sponge up fines from the public.

If speeding fines were shared with whoever reported them, I guarantee 100% that companies would buy real estate every 10 miles along every freeway and put up speeding cameras to automate it.

(EDIT: Looks like you also already predicted the speed trap cottage industry in another comment. Oh, well, I'll leave this one up too)