Used to be that anyone wanting to get off at the next stop was standing in the aisle by the door / platform when the bus arrived at the stop. Nowadays, when boarding, you're never quite sure if, after stopping, someone upstairs takes this as their cue to leave their seat to get off. (Not complaining, this is clearly safer, but slower, and can lead to unintentional boarding before everyone has got off). I'm not clear on when or why this change of behaviour took place, there was a long gap in my bus usage between youth and, er, seniority.