Finland is virtually 100 % cashless. Open markets, grocery stores, restaurants, second-hand shops, flee markets, etc... — they all accept cards. I cannot recall a single place that didn't accept cards. They do accept cash too, though, but most people nowadays use cards.

I have been living in Athens for a few months now. Most brick-and-mortar places, if not all, accept cards but when you go to an open street market, it's cash-only. Also, if you buy something like tobacco, they only accept cash even though they have POS systems in place. It has something to do with the taxes (or circumventing them?).