It's not sci-fi, it's happening today. Go to an Amazon Fresh store and look around - they have literally hundreds of cameras, and several cameras pointing at every single section of shelving. They are tracking your behaviors, how long you stand in a particular place, how you walk around the store, when you touch items, when you put items back, how long you look at an item, whether you're likely reading the label, the list goes on.

Companies have also had, for like a decade now, advertisements in places like malls with cameras to track engagement and how often people look at it and what number of people look at it.

Amazon Fresh also started sending me flyers in the mail after I visited a single time. I get them multiple times a week.