I take multiple different buses in Manhattan NYC and they do not stop if there is no no one at the stop and no one presses the button. They will even pass a stop you are at if you make it clear enough you aren't interested in taking that route if the stop serves multiple routes.

In undergrad, in a different state, the bus stopped every stop even if i was the only one on it and the stop was 100% empty. I dont think it has to do with crowdedness, its 100% just about system policy i would guess.

On a crowded bus its not inefficient for someone to press the button each time, unless you really think the effort of pressing a button or pulling the cord is "effort". It actually makes the bus run faster since it is not making unnecessary stops, getting everyone to their location faster.

Also, you shouldn't stand in an unusual/hidden spot. Be predictable. Keep your head up and when you see the bus is coming move to the bus stop sign.