I used to work at a place where our work product was kept in safes. They had these funky electronic locks, and instead of having notches on the dial there was a little LCD window on the top (facing the ceiling). Whereas most LCD manufactures try to get a wider viewing angle, the manufacturer had gone the other way, so you had to hold your head in exactly the right place or you couldn't see the numbers as you dialed the combination.

There was no way you could shoulder surf the combination. Even if you planted a camera the head of the person opening the safe would be in the way of the camera's sight line.