I really just don't understand why life safety laws are such a hard concept to grasp.
If you build a S & B's it has to comply with building code, electrical code, etc., etc., and those are in form a permit which has been signed off on.
If you drive a vehicle on public roads it must be built to a certain safety standards, the FMVSS, the proof of that compliance is a manufacturers certification label in the drivers door jamb.
An RV, a vehicle / living quarters hybrid, must conform to BOTH of those type of safety standards with its tires. wheels, brakes, hitch frame, 120 volt electrical system, propane system, fire egress, etc., etc., etc.......