I drove a tow truck in my younger days, we were a AAA contractor. They came by once in 3 years for an equipment inspection, never asked for a list of driver's that I am aware of, and as long as we answered a certain percentage of calls within a given time frame they renewed the contract every year. I am not sure any of the tow companies out there could vet 100% every year. I would venture to guess they are vetted with the original contract, then inspected every few years, if then.
When it comes to RV's a lot of companies won't touch them, we did not, and the nearest truck that would was almost 75 miles away. The problem with being so far, is they have contracts in the local service area which they have to meet before they could come out to ours. I have a feeling GS and Coach-Net are the same, and the reason why some folks have awesome service, and others don't.