This week we had a massive breakdown of the computer system, which runs all mayor credit card transactions in Denmark. It was impossible for people to pay for goods or use machines for parking tickets. A lot of Danes had to stay home because they could not enter buses or park because most public transport no longer accept cash due to the risk of robbery and manned banks are seldom due to the cost of having employees talking to customers. In many cities you no longer can be serviced by your bank manager. You have to use the computer at home or make cash redrawals from ATM’s. And the ATM’s were down and closed due to the breakdown.
So as a tourist you will face problems whenever this happens because the parking firms still collect fines even when you cannot pay by credit card on the unmanned parking lots.
It is safe to say that it would be a costly trap for a tourist to fall in, so I have to state that it would be safer to find another country to visit.