Oh ok. But to refute your forest idea, while there are forests a few miles outside those cities, you can't easily walk to them. There also aren't any forests near those major cities where you wouldn't immediately be noticed by park rangers if you tried setting up a random tent. Abandoned buildings don't get daily police sweeps whereas parks do get sweeps because of lost/injured at nightfall when the parks close to everyone without a camping permit. And legal camp sites are very popular so you wouldn't be getting away from people- like those who have their playlists blasting out their phone while hiking.