This is a corollary to the fact that the software in your head wasn't written by you. Ie you see more with your brain than with your eyes.

Artists call this color blindness. Ask a newbie painter to paint the color of the sky. And then ask them to take it outside and compare it to the real sky. Pretty different huh.

A large part of this normalcy field is due to marketing. Things need to look and feel somewhat familiar so that they can be sold.