The point isn't explicitly connecting the cash purchase directly to you. The point is there are plenty of ways to attach payment methods directly to you and onc

The point isn't explicitly connecting the cash purchase directly to you. The point is there are plenty of ways to attach payment methods directly to you and once that's happened anything else related to you can allow inference of further purchase data. For example, store POS system tracks nearby MAC addresses (simplest to do, very archaic). You always have your phone on you. Game Over. Even if you pay cash, if you've ever paid with a bank card connected to your identity next to that phone a logical inference can be made that the cash transaction XYZ is related to pseudonymous ID ABC if phone P's identifier was present at time of purchase. That's what the entire point of things like Google Wallet/Pay is. Another means of directly attaching payment methods to your ID. Once that bank card is connected to you all transactions for that card from any source is also connected to you. From that every ID present at time of purchase is one step removed from you. And so it goes...