Stick people don't own mirrors.

A stick person may as well look at its neighbour if it wants to see what it looks like. Or, if that won't do, stick people spend time by the water, looking at the surface, or through the surface, depending on what they want to see.

It never occurred to a stick person to desire a better reflection than what nature provides, so they never bothered to invent mirrors. Certainly a pond's reflection isn't as smooth as a mirror's, or as constant, and maybe the colours tend to be a little off - but a stick person's needs are simple. Stick people don't worry about the details, the lines, the dots, the tones, the texture. So long as they see two eyes and a smile, they are happy.