Those cameras aren’t usually easily or cheaply adapted to surveillance. Most are really simple and don’t have things like reliable time sync. Also, road jurisdictions are really complex and surveillance requires too much coordination. State, county, town, city all have different bureaucratic processes and funding models.

Surveillance is all about Flock. The feds are handing out grants to everyone, and the police drop the things everywhere. They can locate cars, track routine trips, and all sorts of creepy stuff.