This is something to focus the mind between security an convenience.
constantly turning wifi on and off may be more hassle than some people want.
leaving the device at home is certainly more hassle than I want! (I mean I bought it to use it.)
yes, they actually mass tracking, (link is already posted now.)
And as I said in the first, you don’t need to connect, you only need to probe for networks, (something your device near constantly does…)
but that doesn’t answer if they track individuals… the answer to that question is also yes.
(Tracking smartphone Wi-Fi signals reveals curious journeys on the London Underground)
they have/do track individuals to see what route choices passengers make in their networks.
This is not just available to governments…
The data given up in the wifi probe includes every network your device ever connected to. (your device is constantly looking for it’s past connections e.g. constantly polling “home_wifi” are you there.
and probe monitors are surprisingly easy to make, (https://null-byte.wonderhowto.com/how-to/log-wi-fi-probe-requests-from-smartphones-laptops-with-probemon-0176303/)
Here is a practical example. (I’ve just made this up, it’s not a real person)
Say I’m in a coffeeshop in Oxford UK. and have a device that captures probes.
A person arrives and I see their phone is searching for “oxford tube”, “Starbucks”, “SEH FELLOWS & STAFF”, “McDonalds free”, “SKY9BFBB” and “2CGuest”
I can identify the woman visually as I only see the probes when she enters the shop.
Do you want to tell me where she has previously eaten, (Mcdonalds) drinks (Starbucks), gets her car washed (2c), where she lives and where she works… SEH, St Edmunds hall (part of the university.) we also know she’s gone to London by bus/coach at least once using the oxford tube coach.
Here is her preferred car wash. (look for the purple dot.)
Here is her home…
Note this “woman” never signed up or subscribed to being able to be monitored… all she did was connect to a few networks and then walk into a coffeeshop.
It’s services like Wigle, (that have gamified war driving) that gave up all her privacy in a fast easy and free way… - Wigle users have gone past my house, my wifi SSID is on there, and if my probes are captured, (say at an airport) potential thieves will potentially know that I am out of the country. AND where I live.) - I am not a wigle user. someone else decided to make that decision about my privacy (and potentially my security) for me! (you can search for yourself and see if your WIFI is there.)
Whether it is actually used, or who may be using it, is difficult to say. (I can’t imagine authorities leaving such a tool on the table. - especially when they don’t need to collect the geographical data, and only need to record probe data.
(whilst TfL declared that they were collecting data, I’m not sure that there is an expectation of privacy on data that you are broadcasting. e.g. wifi probes.)
(to “everyday people” like me, it is not useful to know where you life or work…)