Yeah here we are starting to implement average speed cameras. Instead of cameras at one point that catch people who might momentarily be going over the speed limit, they put one at each end of a stretch of road (typically a section of road without many intersections, over a km or a few, so not city streets), and ticket you if your average is much over the limit.

This isn't the US so we aren't talking flocks, we have privacy laws so while they track plates, I think I read somewhere they are hashed for matching and then deleted after a short period of time (we can only keep personal information for the time needed to use it for the purpose it was collected).

Speed cameras definitely reduce speeds, and we've recently started signposting the hell out of them because after all the intend is the lower speed not revenue collection (the government agency managing them doesn't keep the money, specially to avoid this).