Usage will impact how soon a potential problem with workmanship shows up. Most RV's aren't used often enough within that one-year period to catch all the problems that are looming. Problems like: leaks, poorly placed wiring, electrical issues, and frame issues all take time to rear their ugly head. If a person is only using it once or twice a month it may take beyond that 12 month period for a problem to be noticeable. Does that mean it did not exist from day one? no, it just means the RV manufacture got lucky and met their legal obligation.
Look at GM right now. Are they getting by on saying "hey the warranty ran out, too bad." It didn't work for Ford and the 6.0 either. There has to be legal accountability beyond the stated warranty period in some instances...not just "good will".
In regards to your backhoe example. If he would have had to lose time on the machine because of mechanical issues, would you not credit him?