In another thread that I am unable to find a poster mentioned the button, once used by the second warm-bodied staff-human on the bus to open the rear doors.

On a normal bus one is definitely not meant to use the button positioned over the doors in the middle of the bus to egrete oneself from the bus in traffic, or anywhere.

But is one allowed to use the rear door button on a roastmaster? Is it "allowed", and if so, where is it?