It just eventually gives the shop a bad name so most don't.

Incorrect. In the US, no shop can legally hold a customer's vehicle for "safety reasons". That would be theft. For this reason, the likelihood of a repair shop being pursued in a case of driver negligence is virtually zero. And if that virtually zero chance scenario actually happened, this type of court case wouldn't make any headlines anyway. People get into car accidents every 3 seconds. No one is interested in those court cases, so no one would ever even know that the shop was involved, which means the shop's reputation would be perfectly safe.

^{Source: I was an auto claims professional for 10 years and saw many cases go to court. Not once was a repair shop even mentioned. It's the driver's responsibility to maintain their vehicle.}