Some of these TVs automatically connect to any open wireless network in the area, so that isn’t always an option
This isn't something I've seen in the wild yet (beyond anecdotal evidence which I suspect is due to a misconfiguration), however it is a very valid concern especially considering most ISPs are in bed with the media/advertising industry and would directly benefit from allowing these TVs to connect to these networks and making a deal with the manufacturer to make them do so.
Which TVs do this?