Hmm, yea privacy in public is an interesting thought. I don’t think its ridiculous to say you should have _some_ privacy, even in a public space. It feels like the expectation is that you can be physically seen, but beyond that I don’t see how someone loses all facets of privacy, unless you’re assuming a surveillance-state.
For the longest time in urban public spaces, there was a sort of privacy by means of the anonymity processed. You knew that you would never see any of the people around you. That's definitely completely gone now.
This adds less than you'd think since people are already tracked by their cellular location. Some off-shoot use cases for this are determining where someone travels and when along with who they interact with by looking at adjacent cellular signals.
You can quickly solve where they would be expected to go in their daily life, what route they'll take to get there, who they will interact with along the way, and when they will be doing it.
Combine this with their credit card purchase history and you can also work out what they're going to buy and how long it will take them to eat it.
Albeit noisier, utilizing facial recognition for the same purpose has been in use for a number of years now. They're both identification mechanisms but tracking IMSIs and Mac Addresses gives both better recall and precision than a network of cameras.
