They don't (legally) on city property. That's what we're talking about. If you move into a neighborhood where the city maintains the trees in the common areas (sidewalks, parks, etc.), it's not unreasonable to want to put a barrier between the city deciding, for example, it's too expensive to keep maintaining those trees so they are going to cut them all down.

If I or my neighbor wants to cut down a tree is a completely different conversation.

I appreciate your snark though, even though it's completely irrelevant.