A lot of progressive leaning regions are actively trying to slowly legislate cars out of existence, see the camera system in the UK that's being sttacked by the so called "blade runners".
Fact is cars are real freedom, and the next time the government declares a pandemic and determines that public transit is too dangerous, a car is your only movement option for going outside of bike range.
the gubbermint is coming to steal our cars so we have to live in their bicycle dystopia 
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If I was an evil government with unlimited resources who wanted to track everyone's movements, I'd use the already existing systems of license plates and registration, as well as those cameras toll roads and traffic light cameras use to see license plates and identify who's driving them, and just simply put more cameras up and use them to see everyone's last location. 15 minute walkable cities would be much harder, I'd have to have so many agents manually check every building or park they could possibly be in. Even within a 15 minute walking distance, it's still a lot.
Or just get the data from the GPS enabled device everybody willingly carries in their pockets at all times that either of the two massive cellular corporations will gladly sell.