I can't imagine how boring and bereft of life cities would be if rational HN nerds ran them. Trees? Parks? Where's the return on them? We don't need them!
The trees and parks are available to everyone to enjoy though and can be used for many different things, almost surely to appeal to everyone in some way.
A sports team and a stadium have a very narrow appeal and is inaccessible to a large segment of the population either due to disinterest or lack of funds.
I get your gist here but I think it's pretty easy to make a distinction between these things. Even the most hardened Libertarian would agree that public spaces like parks are a net good.
