I want to believe that some dealers do the inspections. But, i do not. For years before i started doing all my own service i would walk around outside and watch work being done in the bays. I became friends with the diesel tech and actually got invited back to help with my truck and hang out almost every time. I never left there without offering the tech cash or lunch. They never accepted but i always offered just to make sure i had not cost them due to my being there.
What i usually saw there was the lowest paid guy, the high school kids, and guys i had not seen before and did not see the next time i was there do the oil change and free inspections. I never understood why they were so low on the rung. They could tell a car was perfect or falling apart needing thousands in work without ever even once looking at more than the oil plug. Getting a new filter with your oil was a crap shoot. I guess they could tell how well it still functioned by the look, smell, and taste of the oil. They must have relied heavily on internal bypass valves. These guys were good. Completely in tune with someones vehicle and able to fill out reports from four bays over in a matter of seconds. They could also tell when a vehicle was overloaded. They would rebalance the weight by removing change from the console to buy sodas and a candy bar or four.