I thought California law was to let the pedestrian fully cross, but apparently not:
> In California, the law does not state that a driver must wait for the pedestrian to fully exit the crosswalk or the street before they proceed on their way in their lane. A pedestrian must be safely out of the driver's path of travel for them to begin driving again.
If you had to wait for all pedestrians to be out of the crosswalk, there's plenty of places where turning would be essentially impossible -- and there's an argument to be made that anywhere with that much foot traffic ought to be turned into a pedestrian-only zone, well, right now there are both cars and pedestrians and requiring the crosswalk be clear before going would make things even worse.
NY prohibits driving in the occupied half of a crosswalk. i.e. from center line to the curb. This is almost impossible to obey in NYC with heavy ped flows but it is a sensible way to combat drivers clipping you from behind.
I thought California law was to let the pedestrian fully cross, but apparently not:
> In California, the law does not state that a driver must wait for the pedestrian to fully exit the crosswalk or the street before they proceed on their way in their lane. A pedestrian must be safely out of the driver's path of travel for them to begin driving again.