This is presumably one reason why Apple has stopped broadcasting your real MAC address while doing SSID probes, instead randomizing it.
The other half doubled down on MAC address tracking tech, arguing that it still generates meaningful data - http://www.euclidanalyticsblog.com/2014/08/beacons-and-wi-fi... Although I've heard they've started to move toward video and facial recog.
We were so small at the time of the announcement last June that we thought... "Why don't we just build a door counter. How fing hard could that be?"
...turns out it's like way, really fing hard.
But here it is - http://i.imgur.com/zLUMAG8.jpg?1