It's a traffic counter. 

Gone are the days of camping at an intersection with a clipboard and folding chair.

Not sure, but if you don’t find any answers here try r/whatisthisthing

That is true... it could also be for a surveyor (??)

hmm ok. I was wondering because speed cameras or red light cameras are waaay bigger. Never seen these mini cameras.

Probably put up by local PD. Or used to track traffic violations. There’s a lot of them in LA

What is this mini camera on the corner traffic lamp post?