> In the real world, this happens if someone has planted a tree in their garden and people like how it looks, then when they want to cut it down, "the community" would like an opinion.

I wouldn't actually put this forward as an argument for the concept of "community ownership", but I will point out that there are many circumstances where the ownership of trees on your yard is actually significantly decided by the community you live in. Whether that's your HOA, or city regulations, or tree law, what you do on your own personal property is often not just your own isolated thing.