Wifi beacons were deployed in London[1][2] as part of advertising systems on waste bins. These logged your MAC address as you passed by and allowed targeted advertising. I believe they were removed once the rollout was publicised and people rightly kicked up a stink about it. It was an opt-out system because if wifi on your smartphone was switched on (which most people probably do) then it would automatically log your phone's presence. Users would have had to switch off wifi to avoid being tracked.
Do people normally have wifi enabled when they're out-and-about? I turn it on when I'm at home/at a friend's house, but otherwise turn it off since there's no wifi to be had, and it's just an extra drain on the battery.
I do what you do, but I strongly suspect that most people never think about this, and don't know how to turn it off. The same people who don't know how to turn the flash off on their cameras and leave it on to take pictures of fireworks.
I switch WiFi off when I leave places with WiFi connection but sometimes I forget to do it.
I know people that think that the phone they bought "has Internet" and they must pay a monthly fee for that. They don't ask themselves how that happens so I guess that some people never turn their WiFi off unless they must learn to maximize battery life.
While I was using "GPS" as shorthand for "automatically determined location", technically doesn't the GPS receiver work better/faster when your phone already has a rough idea where you are?
Yes, most people I know, certainly. For example, since my phone uses Wifi at work and at home, my phone uses it most of the time.
I'm not going to turn off Wifi when I leave work and then turn it on again when I get home... I've never even heard of anyone doing that, it sounds pretty annoying to have to keep track of...
You can get apps that do it by using cell IDs (Smarter Wifi manager is one that I'm trailing but its terrible). It means not having to have GPS switched on for Geofencing.
So now I need to have my phone ping GPS periodically (which takes longer without wifi for guidance) to check my position so it knows whether it can scan for access points it knows?
Personally, I think I'd rather just have it scan for access points. Apple's MAC randomization has the right idea (if perhaps an imperfect implementation)
I purchased a Virgin Mobile handset and associated activation card. The phone is not tied to my name at all since I paid cash for it and I pay cash for the $35 top-up cards monthly. I activated the phone as "Prepaid Caller". I use no apps, only text and phone. My needs are basic. I have unlimited data for $35, so I never use Wi-Fi, and when I'm home, I use a laptop.
[1] http://www.bbc.co.uk/news/technology-23665490 [2] http://qz.com/112873/this-recycling-bin-is-following-you/