Where to begin... Of course I take my car to a trained mechanic. I go to the mechanic, tell him what I want done, and he does it. If schools operated this way, I wouldn't be homeschooling my children. If my mechanic were to consistetly send my car back to me in worse condition than I sent it to him, I'd find a new mechanic too.
I'll go you one better.
If your mechanic put a camera in your car, and began asking you probing, personal questions; and if, when you said, "Look, I just wanted you to make my car run," responded, "Everything related to your car is my business" -- you'd fire him.