Germany is still one of the rare places where it's totally fine to buy a Porsche with cash. There was a good article (missing the link, sorry) how the Italian mafia uses this loophole to launder money.
And another thing is credit cards in restaurants. We just had a big dinner with friends, were the last ones to leave from the restaurant. They advertised credit card payment, but for some reason the machine was not working when we needed to pay and we went to the ATM to get a pile of cash. It's not the first time this happens and not the first restaurant either. I've never had issues paying with card in any other country.
To contextualize: As it is now dealerships and any other merchants have to document buyers (by showing id) purchasing with cash above 10k€ and may ask for proof of origin of the money.
In 2027 all cash purchases above 10k€ are forbidden due to EU law and purchases above 3k€ have to be documented.
And another thing is credit cards in restaurants. We just had a big dinner with friends, were the last ones to leave from the restaurant. They advertised credit card payment, but for some reason the machine was not working when we needed to pay and we went to the ATM to get a pile of cash. It's not the first time this happens and not the first restaurant either. I've never had issues paying with card in any other country.