I’m not a huge fan of right-turn-on-red but one thing I don’t often seen brought up is that right-turn-on-green is problematic as well, for this very reason. When your light (to go forward) turns green, the pedestrian crossing on your right often also turns green, which means there are now pedestrians trying to cross your path. It’s definitely better because you’re only have to focus on pedestrians and not traffic, but “green=go” is a thing that has led several cars to almost hit me at street crossings.
Better than right turn on green, where the same thing occurs. With right turn on red, cars must stop before turning. Furthermore, cars are not permitted to turn if there are pedestrians crossing.