That’s not true. The classic experiment is to write a word on a piece of paper, then show it to a mirror. You have to flip the paper over to show it to the mirr

That’s not true. The classic experiment is to write a word on a piece of paper, then show it to a mirror. You have to flip the paper over to show it to the mirror, and most people flip the paper horizontally. Thus the word will appear to be backwards. Flip it vertically instead and it will appear upside down. The key observation is that the mirror reflected the light from the paper back to us, but it didn’t flip anything; we flipped the paper, not the mirror.