I have never really stayed at places that can be called RV resorts, it just does not fit our travel style of usually staying a few nights here and a few nights there. Sure we have stayed at a few places that call themselves "resorts" just because they had a swimming pool or such. That is unless you count KOA's as we have stayed at a handful of those, though mostly we prefer the smaller private mom and pop sort of RV parks, as well as public campgrounds, etc.
Having said that my take on the problem is that it is all about the money, and few individuals have enough of it to invest in buying and developing a campground the right way. Even all but the most basic small basic rv park with 20-30 sites will cost on the order of a million dollars to build these days even in out of the way, less than prime locations. Sure there may be exceptions, if you find the right location, you may be able to build something for less, if the location already has municipal services like water and sewer. I knew someone that build an RV park about 15 years ago across the highway from our family business, this was a 30 site all gravel rv park on the side of a terraced hill with some pine trees, and a couple of small ponds, and a small portable building / shed laundry room just big enough for 2 washing machines and 2 dryers. At one point while it was still being built they told me that they had spent over $200,000 just on the sewer system and oxidation pond. They eventually sold it at a loss for around $350,000, I think due to health issues, after 5-6 years, during which time the place was always a bit of a dump, the biggest problem was not enough gravel so the red clay mud would seep up through the gravel making it impossible to even walk around without getting your shoes covered in red clay. From what I have seen the new owners have fixed things up some, built a clubhouse, brought in more gravel, paved the central entrance drive, etc. At a cost of what I don't know.
A quick google search shows that their nightly rates are $30 per night as of 2019, I suspect most of their customers are contractors so probably paying by the month, I am assuming around $450 per month, which is the typical going rate in the area, for round math sake lets call it $500 per month. Lets also assume hands on owner couple for such a situation to handle check in / out, rent collection, mowing the grass, and doing basic maintenance with in this case perhaps a $600,000 investment, buying and refurbishing the rv park. Lets assume that was $600,000 cash best case, not financed through a bank.
If they maintain 80% occupancy $500 per month we get (30 x .8 x 500= 12,000) $12,000 per month gross income, assume no overhead cost, no taxes, nothing else it would take just over 4 years for payback of their initial investment. Now we all know there are going to be significant overhead costs, even before we count the labor. We have taxes, both income and property tax, likely municipal services cost (water, perhaps sewer in some places, trash pickup, etc.) that are not directly passed on to guests, not to mention liability insurance, workmans comp if they have employees, etc. So in reality I would not be surprised if these expenses were to add up to more than half that $12,000 per month direct income, lets say that leaves $6,000 per month to pay back the initial investment all before paying the owners any salary to work here likely 10-16 hours per day. So at best we are looking at 8-10 years payback while the owners are providing free labor, this starts to make a regular job look appealing. This only gets worse with larger RV parks, which require a bigger initial investment, more employees, etc.