[jaggederest]

If you do not believe that is already true on multiple axes, you are probably mistaken. The combination of automated license plate scanners, phone beacon data, and behavioral metrics make that relatively straightforward to get, in aggregate.

I worked on a project where we could tell how many users were in a given store at a time (historically, not realtime) based on wifi traces, mobile data aggregation from carriers, and bluetooth pings. We could generally back it up to even general demographic data like how much disposable income the users were likely to have. Interesting project, deeply worrying how much data is running around out there.