Actually, there is. In the better retail video systems, video is time-synced with the registers. I'm not sure how many are doing it right now, but indoor track

Actually, there is. In the better retail video systems, video is time-synced with the registers. I'm not sure how many are doing it right now, but indoor tracking and indoor mapping people would be foolish to not sync their data with the registers as well. Put another way... It is a trivial matter to know that it was your phone at the register when your debit card was used. But they would still only have MAC address and charge, credit or debit card info. Of course... that may be all they need.