Now I get it. Heard a guy at work complaining about this...he got one of the tiny NJ ouse things on a trailer, called it an RV, licensed as such, and stuck it on some poperty he bought to use as a hunting/fishing cabin. He dodged a bunch of building code requirements...for now. If this goes through, there's electric code requirements, foundation requirements, etc.
This does kind of make sense as a fed issue for actual RVs. If they had to meet code everywhere they parked, with different codes at each location, it would be virtually impossible to use an RV as intended.