I do wish we could solo in state parks but honestly we are fortunately they allow us to dive on the property. Giving them a hassle over it could result in them sayings "It's not worth the trouble" and ban cave diving altogether. I also don't personally like the cave solo card idea. As others have said I see more issues arise out of pushing this issue than it will solve.

1. We don't need a card for everything. IMO it won't make it safer it will only require me to pay another fee to get a card to do what I already do (where allowed, of course).
2. Pushing for this at state parks may only end up in solo diving being banned in places it's currently allowed.

There are plenty of places one can dive solo. It's fairly easy to find a buddy to dive the parks and worst case there are still many solo options. It would be great for more freedom but it could also backfire and result in fewer options.