Buying a burrito at the food truck one time I asked for a receipt to expense it. They used some iPad app for stuff like this. Somehow, the receipt appears on my iPhone. How? I never gave them my phone number. I couldn't think of anything other than the one device read the other. Without me ever knowingly giving permission. Key word being knowingly. Damn apps have so many permissions you've given away so much its not the app that's the product, its you. THEY should be paying US!
I read an article one time where they took an android phone and an iPhone, two of each, and drove around the DC area. One they put on airport mode, supposedly WiFi is off. The other they actually turned completely off. Afterwards they had an IT guy run software listing off all the GPS data generated by the phones. Both phones, on or off, recorded every location in real time. Even the names of restaurants and shops they went into.
Amazon sells a whole bunch of products designed to eavesdrop and record every sound uttered in and around. Go ahead, DYODD, read up on all the disturbing stories. Amazon also sells a "security" camera that is designed in such a way as to facilitate interfacing with other systems, with face recognition, and allowing people- just regular untrained people- to tag suspicious characters as, suspicious characters.
China has introduced a system capable of recognizing faces at some astronomically scary rate- a million faces per second. Well there are a lot of Chinese. And they want to know, did you step into the crosswalk early? Did you frown when talking to that official? Or laugh inappropriately? Better not. Because this is no joke. Millions of people no longer allowed to fly, or take the train. They sure aren't laughing.
Neither should you.