Concur. The dealership service department is like no other service. We ask for a service and the dealership provides it. Yes, we scrutinize the bill (and we should), but in my experience the dealerships will fix any errors -- just like your appliance repair person or your roofer, etc.
I believe that most service advisors and technicians want to do the right thing. In that regard,we are all human and people make mistakes, even people in professional service industries where I work, such as accounting, law, engineering, etc. When a mistake is made, we try to fix it. I can also tell you that I have had dealerships mess stuff up. In each case they made it right or at least offered to do so without any argument.
One thing I have found is that some dealership service departments are becoming gun shy because of customers who do stupid stuff. In this regard, I recently watched a customer demand that the dealership fix the whole side of a beat up car where the damage was a tiny dent by the rear bumper. The dealership had no issue fixing what it damaged. The fight was over pre-existing damage. In order to combat this, a local Chevy dealer takes pictures of the car with an iPad when they do the service ticket write up.