Why less time in nature?

http://www.msnbc.msn.com/id/13460467/

This study found that Americans are spending less time in natural surroundings like national parks because they are spending more time watching television, playing video games and surfing the Internet.

I expect this is true.

However, I also expect that part of the reason fewer persons are visiting natural areas is that it costs more. Entrance fees to national parks have been increased, or created where there were none before. To the working poor, $20 can be the difference between whether or not they can afford to go somewhere.