This was in Sainsbury's. The girl, I'd guess at about 14 years old, was coming out of the loos infront of an old lady with a zimmer frame. The girl held the door open for her (as you would for anyone IMO) and the old lady started screeching at her that she could manage very well on her own and to let the door go immediately! The girl was obviously hugely embarrassed but continued to hold the door open as letting go of the door at that point would have meant it hitting the old lady, but the lady was screaming at her at the top of her voice and being really rude, so after about 10 seconds of looking to be frozen in panic, the girl let the heavy door swing shut, with the predictable consequence of it knocking the old lady backwards (not onto the floor, just back). Cue immediate outrage from shoppers running to help said old lady and the girl bursting into tears. AIBU to think that she was right?