A mirror doesn't mirror left-to-right, it mirrors front to back. The clue being that you're looking at a reflection of your face in a mirror, not a reflection o

A mirror doesn't mirror left-to-right, it mirrors front to back. The clue being that you're looking at a reflection of your face in a mirror, not a reflection of the back of your head. Of course since nothing but a mirror can do that in day-to-day life most people expect a mirror to do a 180 degree rotation instead, leading to this confusion.