How about this as a solution.
Eliminate all discounted passes as everyone in the USA feels they have contributed in some form or another to everything they feel they are entitled too. By eliminating theses entitlement passes, everyone is equal, everyone pays equally, everyone can complain equally.
I have both the Senior and Access pass. If they were taken away from me, whoppdy-do. It won't stop me from visiting. I probably donate more to the National Park Foundation than all the entrance fees I didn't have to pay or all the discounts I received. Gimme-Gimme-Gimme, the cry of the baby boomers!