We use a tap card system, with readers at every door, and people are often really awesome about making room at the back. People will even get off and hold the door open, while everyone else jams in. It makes good sense when you're getting off in a couple stops, because when you get back on, you're still close to the exit.
My husband grumbles about people on disney busses who block the aisles and refuse to move back, make room, get cozy, etc. He says the same thing you do - were all going to the same place, so why does it matter if you're near the exit? You're not going to miss your stop! One of these days he might say it loud enough to be heard by more than just me.