I think that part of the problem is that people try to ‘out-think’ the elevator by pressing either the opposite button than the direction they want to go or by pressing both buttons. I once worked with a person who used to work at an elevator company (Otis). That person wrote the software for elevators and told me about the logic used. It surprised me how sophisticated it was for something that could only go up and down and travel to a very limited number of stops. Being efficient with those constraints is very difficult, but when you add in the ‘bad behavior’ of some elevator users, it’s even worse.