When you pay cash you always have to do that face to face. And when somebody has seen you, you are identifiable. When you use crypto currencies you have to give your business partner at least a wallet, and that might be tracable back to you as well. I think it is a question of personal taste under which circumstances you feel more anonymous.

A blockchain backed up by gold, I think I have read that in Venezuela they have plans to launch something like that pretty soon. Within a month or so, because their oil backed up blockchain had a good start.

And the 85% cash transactions, that differes in every country. In Sweden there are only 5% of all transactions still cash. Some banks there do not even give out cash anymore because nobody wants it there.