Germany has a very well established electronic cash system in the form of Girocard because the overwhelming majority has a Girokonto and thus no need for a separate payment method. So why should any business in Germany go through the trouble to offer additional payment options for the extremely few cases where a customer cannot pay via Girocard or with cash? If you are frustrated that you cannot use your card you should blame whoever issued it to you. It's their responsibility to convince businesses to offer their payment method.