I am familiar with piecework-type pay arrangements. And while I would never agree to work for a company paying piecework, I understand that it’s legal to do so. Piecework pay is common in some industries, such as electronics assembly.
What I am struggling to understand is how it’s legal to expect a mechanic to perform inspections/ tire rotations/etc. for free, or to pay the mechanic an unrealistic “warranty time” for work done under the factory warranty when customer-paid pricing guides would indicate a much longer time to perform the repair. Similarly, if the service manager decides to provide a free or reduced cost repair to appease a customer, that is NOT the mechanic’s concern, nor should that affect what he gets paid to do the work.
Of course, I would not expect the mechanic to be paid for fixing his comebacks, but that’s not what we’re discussing here. (It should be noted that when I was an inexperienced technician, many years ago, I did get paid, even to fix my own mistakes, as that was accounted for in the low wages I was receiving.)