I did... the one I work in.

I've got my own tire machine. And my own tools, plus a couple specialty tools.
I'm an auto mechanic, and their prices blow even my mind. Even though MD is expensive, $100 an hour is pretty obscene, even for a dealer of some kind. Hell, the luxury car dealerships around me (yuppieville area) are only ~$120 an hour. I wish I could charge $75 to install 4 tires, let alone one.

Hell, even the cheaper/better/nicer other shop I use wanted close to $100 to install a chain. I took one look at that, and ordered a chain breaker. :Flip: