Lot of people have already mentioned that that person might have been disabled or short buy I see this problem at my place for a different reason.

I live in a tiny dorm room so once my trash is full I need to empty it as there is just no storage space for it.

Only problem is that we have far too few trashcans for residents, so they are almost always full. There is no real other option than to put the trashbags next to the bins.