Regarding the embossed credit cards and using the old click-clack device, here in Germany, the only legally required payment method is cash. Businesses can accept debit cards and, less likely, credit cards, but if the power is out or the electronic card reader is not working, you are required to complete the transaction with cash.
If you are in a shop, for example, you can leave your purchases behind and walkout, but if you have consumed food, used a service or filled the car up with fuel, you will have to complete the transaction with cash - even if it means leaving your car on the forecourt and walking to the next cash machine to get cash and coming back.