Fences in the past were mostly symbolic. If your neighbor wanted to get past it, he could usually just walk over it. Enforcing privacy is an equivalent of contemporary closed-off neighborhoods, with cameras and guards always on post.

The benefit you gain from making a Schelling point is a social kind of thing. It works because people agree it works. Just like all other customs. People bring up privacy of correspondence as an example of ages-old privacy right, but it works only because everyone agrees that reading others' correspondence is a dick thing. If we can relearn to rely more on such things than on direct enforcement, maybe an open world would be better for everyone than private, locked down one.