Nowadays credit and debit card fees are limited by the EU. Around 0.3% per transaction. A 10x reduction to before.
Since then adoption of credit card payment has spread widely in German supermarkets.
That limit is on the interchange fee, not what the merchant pays their payment processor, which is still significantly higher.
Good to know. Then i am still wondering why there seems to be wider adoption of CC in Germany. Or maybe we are only reaching the CC adoption that other EU countries have already seen a long time ago...
Germany is still nowhere close to what's common in other EU countries. Pretty much all Germany's neighbors have much higher adoption of terminals accepting MC/Visa.