I just got a follow-up call from Joe. He said that his guys working at the shop generally don't have much time to drive the cars. Neither of us have any evidence to prove either way so I have suggested that they start writing down the mileage on the worksheets, and to point it out before and after the job.
As far as the actual work is concerned, my position is the same. Joe said that it was probably a miscommunication that resulted in me having unrealistic expectations.