The wandering waves is the reason for the (former) policy that it's legal to listen to anything you can receive. You're on your own property and you own the waves. The exception was that you were not permitted to divulge anything you hear that's not a public broadcast.

That sensible idea was thrown out to favor cell phone companies, which didn't want to encrypt cell phone calls as they should.

With WiFi you transmit as well, so the idea really doesn't quite work.