The garage I go to change my oil has video cameras mounted such a way that you can watch the guy doing the job from several angles. Never have a problem. The shop is in small town so all the customers are local. I am guessing if there would be a problem the guy would be out of business in no time.
I change oil in my tractor, lawn mower etc but I hate the hustle returning the used oil. No shop wanted to accept it. So my wife put on a miniskirt, walked to the same shop I tried before few days later and had no problem. Go figure.