> "Facebook can't tell if it's me or someone else at the same coffee shop."

Eventually, they will tie your various devices to you.

These a chapter / section on this (and FB) in Chaos Monkeys.

https://www.antoniogarciamartinez.com/chaos-monkeys/

That book was published 2+ yrs ago. I can only assume the technology is more thorough and sophisticated now.

p.s. see also Dragnet Nation

http://juliaangwin.com/dragnet-nation-available-now/