I had a student once who hated mirrors in elevators. She said that she didn’t see the point. For me though, mirrors in bathrooms and elevators are a chance to check that I don’t have anything between my teeth, mascara smudges in snowy weather, a button accidentally undone, or hair flying over the place. The public toilet above, therefore, would be rather irritating for me if I wanted to check that I looked presentable. Does that have something to do with vanity?