I'm just guessing? But if there is no seat belt, hopefully, no one will sit there. Now think about this.
Rear facing on a dinette seat in an RV. Head on collision, or even a VERY sudden stop...??? what happens to the passenger facing backwards.
His head will snap backwards because there's no head restraint! He'll end up with a snapped broken neck. I know this is probably extremely rare, but thinking like someone who would design a MH, this is the only thing I can think of why no seatbelt for rear facing seats.
