I have a credit card, but it is paid in full at the end of the month automatically, so for all intents and purposes it's essentially another debit card. Everyone I know in Germany who has a credit card uses it this way. In fact, my bank didn't even ask me if I wanted it set up any differently, so I have to imagine it's not just my social circle handling it this way.
Many UK banks used to issue Switch/Maestro cards which interoperated with the German bank card system so were accepted in German supermarkets, but these got phased out for Visa / MasterCard debit around 10 years ago meaning I had to start using cash everywhere.
When the EU capped the interchange fees in 2015, many retailers started accepting MasterCard and Visa here. AMEX is exempt from the regulation since it's a three-party system and less commonly accepted. I'm not aware of any retailers that accept MC/Visa debit, but not credit cards or vice versa.
How come Germany is so cash positive? Personally I think Sweden has gone a bit far, where some old people have been put in a weird spot where they can't pay because they're technologically illiterate.
which wouldn't be a problem for shopping online if they had a Visa or MasterCard cobrand, as these can be debit and tied to your bank account as well.
It's only slowly changing with some Sparkassen issuing MasterCard debit cobranded cards in late fall (https://www.f-i.de/News/ITmagazin/Archiv/2020/Einfach-mobil-...)
That's a peculiar choice, but I assume the decision was made to appeal to the typically skeptical German market. I do wonder why it wasn't made opt-in, though.
When asking around I got several answers. Everything from a cultural aversion to debt (and spending via cash makes it easier to track your spending), not wanting to be tracked where you shop due to not wanting the government to know (comes from Nazi/East German past), and just being culturally conservative and not really liking change all that much.
I didn't like it as being a tourist meant I was eating out a lot, etc. I had to carry a lot of cash around that I'd only have to pay a fee to convert back if I had any left.
As for why we're so cash positive: one of the factors is privacy. If you pay for everything electronically both your bank and merchants are in the position to build a profile on you. If you use a non-local scheme (e.g. MC or Visa), they can too.
I think the confusing part of your comment was where you consider non-credit cards (debit, prepaid etc.) to be distinct from VISA/Mastercard. That is not the case in most countries. It used to be the case in Germany, but is slowly changing as more and more debit cards are VISA/Mastercard cobranded.
Debit card means you're responsible and take money out of low/zero interest checking account at the principal bank where we Germans hoard our money.
Credit card means you're on shaky financial ground, deal with credit card companies with their fine print, risk punitive overdraft charges, and have probably no idea if you have any money left.
Sadly, things are changing and many people seem to take on irresponsible loans (i.e. for anything except real estate).
Associating Mastercard and Visa to credit and not debit as well.
Mostly banks and retailers colluding together to use a cheap domestic-only POS-only scheme (think Przelewy24, but offline or LINK but at POS).
In Germany, most banks still see these use cases as an opportunity to upsell their loyal customers on their expensive credit card products (not in terms of interest really, but rather because of high monthly and foreign use fees).