Why do US doctors earn so much money?

Doctors world wide are paid better than the average income when compared to the local population. Even witch doctors in remote tribes are considered more valuable. It is a simple supply and demand issue. If everyone had the ability to be a doctor then they wouldn't make as much. The fact is that not just anyone can be a doctor, it does require a smarter than average bear to be a doctor. This same question could be applied to almost any higher profession. Why does a mechanic for a race team make so much? Why does a master plumber make so much? Why does a master electrician make so much? Why does any professional make so much? So much is a relative term. If your a drive through window worker at a fast food chain you could ask the same question of the manager.