Putting on tinfoil hat... how do we know it isn't connecting to our neighbors' open WiFi?

Do your neighbors have open Wi-Fi? I'm a country dweller, but when I'm in town I look at the Wi-Fi list (in horror) sometimes, and it's really rare to see an open Wi-Fi network.

It’s a common fear. People constantly mention it on HN every time the advice to keep a TV off the internet is mentioned. Yet we have never seen proof by anyone, not once, that it has happened. Extraordinary claims require extraordinary evidence.