The biggest difference is there isn't many ways to abuse a plane. You don't sleep in the beds, don't cook and not clean up the kitchenware. You don't clog the sewage systems or fly it down muddy roads. You don't do much of the maintenance on a plane, that requires professionals to sign off. Not the case with a motorhome, using a paper clip or duct tape to fix a system is perfectly legal, just not safe. On top of that, most people in plane partnerships do not take them out for weeks at a time. There is less scheduling conflicts and with planes you can't loan them out to third and forth parties (unless they are licensed pilots also), which is a big temptation with an RV when he kids want to take it to the football game for the weekend.