don't see that everyday

I just saw a woman at the store with her shoes on the wrong feet.  Her big toes were making weird bumps where they shouldn't be, and since her shoes were rather stiff, you could plainly see them turned out.  This woman was probably in her 40s, and didn't appear to be drunk or have any hindering mental conditions.  What the hell then made her not notice when she put her shoes on the wrong feet?!