Basically he is saying he wants to sell off the national forests, blm land, and sell everything to private land owners at high bid.
Obviously there wouldn't be national parks in a Libertarian system that isn't to say though that people couldn't buy up their own land and let the public use it I don't know where you got that shit from his interview because he just said you could go to court if some company or person is polluting your land it's really amazing seeing Americans try and think about a different viewpoint to theirs because you really do just make shit up and choose to live in your own alternate reality, not wonder nobody halfway decent gets elected as president in your country.
I think he is right about the example of pollution he gave. You're assuming it's straight forward to determine if the land or air was polluted by a company or person, but I don't think that is necessarily the case. As he said, you have for example a company some distance away that is emitting pollutants that are known to be harmful. How do you prove that your recently developed cancer is related to it? Isn't it easier to make sure those pollutants aren't emitted, or are at least treated first? Or for example, how do you deal with those that contribute to climate change, or any other externalities?
