I live North and East of Indianapolis about 40 miles and there are lots of storage facilities in my area. I see everything in those storage facilities, all types of campers, from pop-up to mega billion dollar motor homes. Some are covered, some are not. There's no set pattern.
I live in the country, so I see a lot of RV's parked in yards around where I live. Very few are covered during the Summer months, but about 50/50 are covered over the winter months.
I also live in farm country and there are several around that are able to park their RV's (of every sort) inside barns, sheds, and carport style shelters.
There's really no rhyme or reason or logic. It's just a matter of what each person has available and how much effort they want to take into taking care of their RV's. Cover or not cover also depends upon how much the camper is used too. If used every week, it's a royal pain to put it on and take it off every week.
Take your pickin's. Whatever works for you, do it.