Smart TVs & ACR
The most invasive device in your home is likely not your phone, but the screen in your living room.
The ACR Mechanism
Automatic Content Recognition (ACR) is a technology built into the operating systems of almost all modern smart TVs (Samsung, LG, Roku, Vizio). It acts like Shazam for everything on your screen.
Every second, the TV takes a fingerprint of the audio and/or video being displayed. This includes content from external inputs like cable boxes, gaming consoles, and DVD players. It sends these hashes to a database to identify exactly what you are watching, including commercials.
Why is this valuable?
Advertisers pay heavily for "attribution." If you see a car commercial on TV, and then search for that car on your phone 10 minutes later, the advertiser wants to link those two events. ACR allows them to know you saw the ad. Cross-device syncing (via your home IP address) allows them to link the TV view to your mobile phone search.
The Margin Problem
Why are massive 4K TVs so cheap? Because the hardware is a loss leader. The manufacturer makes their profit over the lifespan of the TV by selling your ACR viewing data to brokers like Samba TV.