Interesting views. I checked the "rules". They say:
Caches on land maintained by the U.S. National Park Service or U.S. Fish and Wildlife Service (National Wildlife Refuges)
You will be in violation of federal regulation by placing a cache in any area administered by the National Park Service (US). The National Park regulations are intended to protect the fragile environment, and historical and cultural areas found in the parks.
In addition, there may be local regulations already in place for certain types of parks in your region (state parks, county preserves, etc.).
I think that I would like to be informed that the cache is in an area that costs to park. We should be following the rules, both legal and ethical.