In a right turn on green scenario, the driver mainly needs to be looking for pedestrians crossing and they will be crossing a different direction. In a right turn on red, their primary focus is on cars, limiting their attention on pedestrians. It also encourages creeping out into the crosswalk, blocking people from crossing on a signal.
That makes sense. Being European I’m often annoyed at not being allowed to turn right on red. Allowing it at non-pedestrian intersections would perhaps be a fair compromise.
