I think I have calluses on my butt. I work from home sitting in front of a computer all day and my chair is a wooden chair. Wooden all the way through. No cushion.
Plus, I have very little cushion down there so the bones come down pretty prominently when I sit.
And lastly, the skin down there is rough in those spots.
I know, some of you are thinking “whoa, Rex, TMI!” but Butt Callouses are real people. Get a padded seat. Save your butt!