Membership parks derive all their income from selling new memberships. Buyers have become much more savvy and these arrangements have fallen out of favor. People interested in these type of contracts are more likely to purchase on the resale market meaning less income for the parks. With falling revenues the parks delay or cancel upgrades and postpone repairs. That results in the parks being less desirable, meaning the park has to compete only on price further decreasing revenues leading to a downward spiral. The minimal daily fees, be it ten bucks or increased to fifteen or twenty bo nothing more than cover added costs. The park is working for free. Plus, charging ten dollars to membership guests creates customer relations issues with the full rate guests. They only hear that their neighbor paid ten dollars and they paid forty.
Eventually all this leads to either the park leaving the network to pursue a different business model or just closing the doors because the deferred maintanence exceeds their financial capacity.