Actually all those problems are precisely because NPS does not privatize instead once it figures out it can not provide basic services it grudgingly invites private players with very little freedom to run their business or pricing.
The NPS doesn't control concessionaire prices. All of the problems with the private concessionaires of that want to make a profit, so they put as little money in as possible while setting prices as high as possible.
What makes you think privatizing would fix any of that? It'd just be another Universal / Disney / etc. with overpriced foods AND overpriced admissions
Edit: And this also totally misses the point of the parks to begin with. They're there not just to entertain visitors but to preserve these landscapes for posterity. Privatizing them would totally go against that. We don't need anymore land barons exploiting the masses and preventing them from experiencing the places they have a birthright to.
