The main issue with a cashless society beyond that is that they can deny you access to your money remotely: The Prophet Atwood covered this one back in the 80s.
But I think the surveillance ship sailed some time ago. It seems largely academic that you can be tracked by your mars-bar-level transactions when you're walking around with an active tracking device in your pocket anyway.
I can turn my phone off when I want to go off the Radar.
But these days, the act of doing that is almost as incriminating as having the phone with you at the crime scene...
The tracking of devices can be used for non sinister purposes. TFL used the MAC address of the wifi in your phone to track what routes people took underground between various stations. This allows them to grasp a much better idea of what route people were taking between stations where there are multiple options of changes. I'd put that into the "good use of data" category. But the downside is there was no easy way to opt in. It was kinda opt in by default. During the trial I did make a point of airplane moding my phone every time I went on the tube, just incase. My understanding is that what was once a trial, is now standard deployment on the underground
Lessee now...
Acquaintences. Hmm the nearest to those would be colleagues at work and if I'm with them then using a portable telephone as a tracker would be massive overkill. I don't attend work socials either.
Cool, let's look at proxy data sources instead then. We can tell you're at home based on the way your network usage changes on the DSL... or by looking at the increased power usage...
Many cars have a built in sim card and 4g networking that leaks info...
We can look at your transactions on your payment cards...
Do you have a Garmin or wahoo like device that has blue tooth? Maybe we can detect that going by.
What about your car number plate?
Friends. Ermmm. Nooo don't think I have any of those. If I'm out and about it's almost always entirely on my own. You don't look surprised by that. Why?
Not at all surprised. I spend 90% of my time on my own. This surprises muggles. But I long ago resigned myself that if I am to do the things I want to do (mostly big rides, or geeky stuff), I either do them on my own, or not at all. No point waiting to find someone else crazy enough.
When I lived in the UK, I worked from home (ran my own business), the only times I ventured out were to the library and the supermarket. Once the self check out was rolled out in both the library and the supermarket, I'd go days without talking to anyone, I would talk to myself or sing along to stuff just to remind me that I can speak...
Family. See them once or twice a year, usually at home so a portable telephone would again be a waste of electrons and they're so ancient they still think telegrams are a thing and wouldn't know a portable 'phone from a hole in the ground. MrsLurker's portable telephone is usually left at home and switched off into the bargain.
How novel, that's on average 20 times a year more than I see mine. Tho this is apparently not abnormal for QUILTBAG types, after all, who want's to talk to the lesbian in the family?
But we digress. Noones alone with the internet... or something...
and you're still leaking info, even if you don't realise it...
Which reminds me, I went to a MeetUp event of Girl Geeks in Amsterdam. We were doing icebreaker get to know you type stuff. I turn to one girl. "So you're a Ruby programmer" turned to the next one "You're from Utrecht and like creative writing" to the next "you're also from Utrecht and like knitting". Everyone just stared at me. "That's creepy". "No, that's the Meetup app leaking information and you lot not setting your privacy properly. Oh, and I can tell that 4 of you are Bi or lesbian too, this thing is better than gaydar!"
All of this from information the meetup app leaks...
anyway, digression etc...
Sorry.
J