Cash transactions are anonymous only if most transactions are cash. I take x eur from the bank and give them to you. You put x eur to the bank. That's linkable. And the people sign up to all sorts of savings cards en masse making their transactions at the till completely traceable. It is not about what happens routinely, it is about what can happen. Banks don't give a damn about your transaction history as long as you account balance adds up and neither does the government. With cash, there is an illusion of anonymity. Without cash you actually know what happens.