Originally Posted by murraypaul
Alternatively they could just check people's Facebook pages, where most users seem happy to publish all sorts of information about themselves.
Yes, and lots of them already have had cause to regret it. At least Facebook, dumb as it is, is opt-in so if people want to bare their lives it's their choice. Trackable device ID's aren't opt-in and, in the case in question, are a specific end run around declared privacy goals.