> The real money would be in giving civilians whose footage leads to a successful prosecution for moving violations a percentage of the fine.

I don't know where you live, but around me, the police are so disinterested in traffic safety that roads have turned into a Mad Max free-for-all. Red light running, stop sign running, lack of signaling, weaving in and out of lanes, and general belligerence on the road. That and 90% of drivers are playing on their smartphones. Police departments could get infinite money by just opening their eyes and pulling nearly anyone over.