[potato3732842]

Nothing special. Slight increases in minor accidents and near misses, some minority of which will involve pedestrians or road rage violence Basically the same downsides as anything else that changes the speed via rule or enforcement rather than changing the conditions of the road (e.g. "traffic calming").

[whimsicalism]

i fail to see how adding cameras and an additional penalty will lead to any of those things

[potato3732842]

Because it only affects some drivers leading to higher variance in speed leading to more friction among traffic. Same reason everyone with a brain suggests traffic calming over changing the numbers on the signs.

This is transit 101 level stuff.