Where do you run into places that only take cash so often? Where I am even the guys selling street papers have Venmo as an option (they hate it since they don't get the money in a usable form as easily that way, but they'll gladly use it).
"Your DeKalb's Farmers Market", one of the two largest/most popular farmers market stores in metro Atlanta has never accepted credit cards. They do accept debit cards, so it's not quite cash only, but they take a very hard line one the issue of credit cards, having vowed to never accept them. Doesn't seem to have hurt business any as the most common complaint about the place is that it's too crowded.
I know of a few Chinese bakeries or other Asian bakeries that only take cash (and my wife wants to buy something there). Also, amusement coin ops at the mall for my kid.
In many countries it's illegal for shops to either not accept cards or to charge more for card payments (even though they do cost more, more than 5% of the transaction cost in some cases). I think this measure of hiding away the real cost of card transactions was the main driver for increased usage in earlier years.
Interchange fees are capped at 0.2% debit, 0.3% credit. Somewhat higher (~1.2%) for business cards. These caps do not apply to cards issued outside the EEA, nor do they apply to three-party networks such as Amex.
Despite that this displeases the networks, businesses are allowed to elect to only accept a subset of card categories (i.e. they may decide they accept Debit Mastercard only, not Mastercard Credit or business cards). That said, honor all card rules _within_ a given category have been found enforcible (including that e.g. a merchant can't decide they accept Visa Debit, Debit Mastercard and Mastercard Credit but not Visa Credit - Visa are allowed to say "If you accept Visa Debit and Mastercard Credit, you must also accept Visa Credit")
Processors/Terminal providers will add their own margin on top of these, of course (interchange fees are entirely remitted to the card isssuer)
Pre-pandemic it was still very common in the UK, despite having an extremely high uptake of contactless payments for years. It was mostly takeaways and small businesses like butchers etc. It was changing before the pandemic but I still instinctively ask "Do you take card?" before ordering at a takeaway.
