I would be interested in the statistics of how people camp.
I imagine most RV owners go from their house, take a short drive (under 2 hours) to a full hook-up campground, stay a few days, then return home. For this they do not need fancy refrigerators. I imagine it is more rare to boondock. I have also observed that RV owners will run their generator just to be able to play with it as a toy, even running it just to have one light lit up. It's like they do not know the battery will run a light, or they do not understand how that works, all they understand is household current. Thus, RV manufacturers will appeal to those buyers and offer campground RVs.