In most countries there is a legal rule that establishes cash, which says something along the lines of : Currency notes must be accepted as payment for all deb

In most countries there is a legal rule that establishes cash, which says something along the lines of : Currency notes must be accepted as payment for all debts, public and private. This means not accepting cash is actually illegal. This has been relaxed a bit, in that refusing to take a 500 euro note for a .5 euro purchase is permitted, but either refusing to sell to someone who wants to pay cash or not accepting cash after the sale is not legal.