> cash

How can you presume we do not pay with cash?! How can you remotely suppose one sane mind would not use cash for all sensitive private transactions - books, medicines, preferential (profiling) products etc.?

We use cash in general because nobody in Dignity would accept their own daily matters to be recorded and given to multiple untrusted parties¹, not to mention potentially retrievable by even more untrusted parties - of course the matter is much more evident for all transactions over confidential items!

(¹EU here: 12 public-hybrid-private DBs as per the PSD2 legislation.)