Other than maybe street merchants, can credit cards be used just about anywhere else including small transaction? We recall in past years many merchants required a minimum purchase to use a card.
See this recent post which addresses your question
https://community.ricksteves.com/travel-forum/france/euros-or-credit-cards-in-paris
Just last year I encountered a convenience store/tabac shop that required a 8€ minimum purchase.
Most places will take a credit card or Apple Pay. Some require a minimum purchase. Occasionally especially in smaller towns or villages they only take cash. Carry around €100 in small bills (€10 or €5) and € coins for purchases in these shops and cafes.
During my week in April, I came across 2 sandwich shops that I paid in cash due to being under the minimum. I also paid cash at a street market because that was the preferred choice of the seller. Everywhere else was credit card including the €1 bottle of water from my corner shop.
Not France, we stopped at a small grocery store in Amsterdam on Thursday that had a €6 minimum. Any pay toilet we've encountered so far requires cash.
“Any pay toilet we've encountered so far requires cash.”
One of the first places I used ApplePay was the pay toilet at Amsterdam Centraal Station. All of the Paris train stations I’ve been to have had contactless payment. The rather dreadful toilet at the train station in Vernon did require a Euro coin.
We always take 500 Euro home from each trip for the next trip. These days we don't use it. We have been here 5 weeks and I have used about 30 Euro in cash for the few shops like the butcher that have a minimum. Bakeries and grocery stores the two sites I use every day will allow the card for a purchase of any amount. Transport tickets are all done with cards. We just got back from Switzerland for a side trip to CERN and again used the card for everything. I had gotten 100 Swiss francs and had to scramble to spend them at the end of the trip.