alt Hacker NewsNot just governments, though.
I've wondered if FaceID and the Android counterpart are actively creating an extraordinary labeled dataset for facial expressions at the point of sale.
With users trained to scan their face before every transaction, tech companies could correlate transactions to facial expressions, facial expressions to emotions, and emotions to device content. I can imagine algorithms that subtly curate the user experience, selectively showing notifications, content, advertising to coax users towards "retail therapy".
Any webconferencing app on iOS probably fires up the TrueDepth camera to power background replacement and could conceivably do that, albeit not so responsively. Recommend heading to your provider and opting out of share-or-sell if you can.
Also keep in mind keystroke dynamics can probably do that too and has been a topic of study in one form or another since the nineteenth century vis-a-vis telegraph operators.