That's where the network of CCTV cameras with facial recognition and gait detection come in!
Barreling towards a complete lack of privacy is scary and waving it away as "just don't bring your phone" is massively naive. There are many many ways you can be identified and tracked besides your own phone, because there is so much incentive to do it. Even if everyone stopped bringing their phone everywhere out of fear of tracking, they would _still be tracked_