Valve uses a toolstrigger trigger around the door, I believe. "OnStartTouchAll" is used to open it and "OnEndTouchAll" is used to close it.
I don't know the difference between those outputs and the ones that don't end with "All", but I'm guessing that "OnEndTouch" would close the door when someone stops touching the trigger, which is no good in TF2 - if you have 4 players in the spawn room, all of them touching the trigger, that would mean that when one player leaves the trigger, the door would close, even though there are still other players in the vicinity of the door.
Kind of like how the resupply cabinet stays open with two players next to it, even if one of them walks away from the trigger.