Well that is the capability of security cameras, loyalty cards, credit cards, scanning ID to get booze and a million other identification means. Unless you go to Starbucks wearing a ski-mask, a Faraday cage, and paying with cash you are possibly being tracked for marketing data. As much as I have an natural dislike against rampant corporate abuse, I am hard pressed to find a reason a privately owned merchant couldn't put one of these in their store. When I go to a hockey game I get my ticket checked, my ID checked, I have to empty my pockets, possibly even my bag, and I have to get scanned by a metal detector. But that is something I consent to so that I may go about enjoying the game. I feel as though eventually these types of Mac address scanners, loyalty cards, credit card tracking, and things of the like will just be terms that the stores set that we just sacrifice to be able to shop there. As for me I would just rather turn off my wifi and buy as much as I can off online stores.