I think you've hit the nail on the head. Dealership techs are familiar with the vehicles and are familiar with their issues, so they tend to recommend repair or maintenance of items at the earliest opportunity (even if it is not to the owner's benefit). As a result, those vehicles tend to be better maintained assuming the owner purchases all of the recommended work.Dealerships tend to prescribe more service and many people who use them get items done earlier than Indy mechanics and self.