Look up the YouTube on project Argus that uses drone cameras in like 2010 or something. every moving object inside a city is classified, identified and tracked in and out of buildings, cars and that's just the declassified part. I've talked to people who've told me or shown me a lot more wild systems they've built for retail decades ago to track user product interactions then tied it to loyalty and credit cards so they know what you looked at vs purchased and how long and mood age etc just from video. tie all that to public data or purchased or given data and it's basically game over for being anonymous.