Why Doctors are Highly Paid?

A mechanic was removing the cylinder heads from the motor of a car when he
spotted the famous heart surgeon in his shop, who was standing off to the side, waiting for the service manager to come to take a look at his car.

The mechanic shouted across the garage,"Hello Doctor! Please come over
here for a minute."

The famous surgeon, a bit surprised, walked over to the mechanic.

The mechanic straightened up, wiped his hands on a rag and asked
argumentatively, "So doctor, look at this. I also open hearts, take valves out, grind 'em, put in new parts, and when I finish, this will work as a new one. So how come you get the big money, when you and me is doing
basically the same work? "

The doctor leaned over and whispered to the mechanic .....

..."Try to do it when the engine is running.