Yep these people work at these oil change places for a reason, cause they cant get a job at a real repair facility.
I stopped going to them years ago when I owned my 1992 Mustang GT.
The 1992 5.0 had 2 drain plugs. I was under the car doing some maintenance when I noticed how filthy my front drain plug was and how clean my rear plug was. I cleaned off the front plug and applied a strip of paint on it to see if gets removed during the next oil change. After the oil change I pulled out and parked in the lot and looked under my car and sure enough the front plug was never removed to drain the oil out. I went to the Manager and had him question the employee who did my oil change and he insisted he removed the plug so I made him and the manager look under my car and the Manager fired him on the spot for lying to me and to the Manager.
I never went back and stayed away from these places.
I can understand why people use these places but for a few $$ more you can have the dealer change the oil and know it was done right 99% of the time, I have known dealers to blow engines too.