Just spitballing here. What if for places like Zoos, a sort of collective public resource (even if it is privately owned), you couldn’t buy a membership; instead you had to earn it. You volunteer, and if you do that enough, you earn your membership. If a well coordinated and thorough volunteer management system was in place I could see this reducing operating costs for the zoo significantly enough to impact ticket prices for non members.
In tandem also define membership at only individual level, but make membership mean unlimited entry not just for the member, but also for a guest. I think this could replace the increasingly hard to define family membership.
If such volunteer systems could help take care of not just schedule coordination, but certain levels of training I could see this being a really awesome way for people to become actually personally invested in these shared public resources, which is sort of a part of solving the tragedy of the commons issue. How much training does it take to learn to clean a tiger cage, or sort fish to feed penguins? neither really fun jobs to do repeatedly, but with a volunteer system that also handled a lot of the training? Could an approach like this harness the power of novelty?!