Parks are paying more for everything. Utilities, labor, taxes, interest rates, professional services etc. are going up. Plus the park has to increase their profits or they fall behind all the inflation effecting the ownership.
Also, parks are getting a lot more sophisticated in their pricing and management. Reservation software makes demand pricing much easier. Parks are realizing full parks may not be as profitable as being 80% full at a higher rate. And like already mentioned supply and demand is very much in the favor of parks.
Finally, the $100.00 nice hotel room doesn’t exist in most popular areas. $200 to $300 a night is closer to the norm .