Looking at my last six trips to Europe (most of the time, but not entirely spent in Germany), I remember using my credit card exactly 9 times. Four of those times were on the last two trips, when I used it for a POS purchase of clothing in a store for my SO, who likes to shop and found something fairly expensive she wanted. Of the other five, four were advance purchase from the US of rail tickets; using a CC is the only way to get the savings offered by advance purchase of tickets. The other CC purchase was from a ticket automat in Würzburg when there was a long line at the ticket counter. As I remember, at the time the Bahn ticket automats only accepted credit card payments - you could not use cash. Most of my ticket purchases were for local ticket and regional passes from local (Nahverkehr) automats which did accept cash.
A tenth time I did use my credit card before I left the US to guarantee an accommodation for late arrival, but since I did arrive and ultimately paid cash for the room, by CC was never charged.
I never use a credit card to pay for accommodations or meals. I've found from experience and my research, that the small, culturally interesting places at which I like to stay almost never accept credit cards. I have actually had these places notify me in advance that they only accept cash. To use a credit card for accommodations in Germany, you almost always have to stay at a bigger, overpriced hotel, one that caters to tourists who want to use their credit cards and will pay more for of doing so. Correspondingly, I've never tried to use a credit card in the restaurants a go to, but I have never seen anyone using one in these places, either.
Although I feel I spend less by not having to stay in a place that takes credit cards, I don't feel that the same is true for POS purchases. If my SO finds something she likes in a store that takes a credit card, I'm not going to go out all over town looking for someplace that has the exact same thing for less because they don't take credit cards. I used my card for the purchase to limit my trips to the ATM.
Credit card usage is not without risk. A couple of years ago, I used my credit card to make an annual payment to a computer security company. A week later a 99¢ charge appeared on my card from the same state. The bank explained to me that when a card number is stolen, the first thing they do is make a small purchase that won't be noticed to assure that the card is live before they start using it to drain you account (or sell the card number on the dark web). So they cancelled my card and issued a new one, but I had to figure out all the people that had the card number for automatic payment and change the card number. Last summer, my SO used her card, I think at a restaurant in Kennebunkport, Me. Soon after fraudulent charges began showing up on here card, so the bank closed the account and opened a new one. Again, she had to change the card number for multiple merchants. Six months later, she used the card in California, and the same thing happened.
But my major beef with credit card interchange fees is that they add to the cost of all good that a merchant sells. So we all pay more. The profits from this higher cost goes to pay overpaid bank CEOs and wealthy investers. It's essentially redistribution of wealth, from the less wealthy to the wealthier.