Why teach evolution?

Science (June 5, 2009) has a short interview with Eugenie Scott (subscription required), executive director of the NCSE. One question irks me:

Q: Why is it important to teach evolution? Can't doctors and most life scientists do their jobs without accepting evolution?

E.S.: You can be a mechanic without understanding the niceties of the internal combustion engine. [But] wouldn't you rather go to a mechanic who has the big picture?

Why is it important to teach evolution? Because evolution is true. Because it explains why we are the way we are, why we develop from fertilized egg to adulthood and old age the way we do. Because without it we cannot properly understand our own place in nature, and that is one of the most effective incentives for caring about the environment. Because many advances in medical research rely on an understanding of evolutionary mechanisms. Because pests, parasites, and infectious disease cannot be controlled without taking evolutionary dynamics into consideration.

When my car is broken, I trust my mechanic knows what he is doing. How can you trust that if he doesn't understand at least the basics of how the engine works? Perhaps this is not required of everyone who ever works on your motor, but at least some supervisor at the shop should. When I am sick and go to the hospital, I might be treated by people who do not believe in evolution, but I have trust that there is an M.D. around who knows the details of how antibiotics function, and how genetic diversity affects treatments. Both of those require some understanding of evolutionary theory, if not outright belief in it. Medical doctors can believe any crazy things on their day off, but without accepting it in their professional lives they are putting patients at risk.