The dealer mechanics are doing what the dealership owners tell them to do, make good money off service to justify their salaries, etc. If you look at it that way, they are good at doing that. Nobody forces anyone to go to a dealer for service unless it is something very esoteric that only a dealer can do, either because of complexity, because you don't have the tools or because you have enough money to not worry as long as the work is done correctly and there is a warranty.