When you are standing in an elevator, you can always check your hair and touch up your makeup. The question is, why are the mirrors there?
Mirror, mirror on the wall
There are a number of reasons why there are often multiple mirrors in an elevator. For one, a mirror helps people with claustrophobia. It makes the room look less small and oppressive, which can reduce anxiety feelings somewhat. You feel less confined. Another reason for mirrors in an elevator is that it makes you feel safe. You can see through the mirror exactly how someone is behaving, and the chance of theft, for example, is also reduced this way. A mirror can also help when you are transporting things, for example. It makes it easier to maneuver yourself in and out.
Distraction
An elevator ride sometimes seems to take hours. You're standing with a group of people, the majority of whom you probably don't know. There are some awkward conversations and everyone is thinking the same thing: are we almost there yet? Mirrors in an elevator can provide some distraction. By taking a quick look in the mirror, you can see how your hair looks and whether you might have shot out with your mascara. You quickly wipe it off and before you know it, the elevator stops on the floor you need to be on. You've survived again.