Mechanics are clever and drivers are stupid. How many people take their car in and try to tell the mechanics what the fix is rather than describe the problem?

It's not about being clever or stupid at all. It's about being inconsiderate or unthoughtful. People of all stripes are guilty of that. Having been on the wrong end of it enough times I try very hard to give just a little thought to the role of the person to whom I'm speaking. When I go to my mechanic, I am the user and I want to make it easy for them to help me.