Just an example of a large municipality doing this: In NYC food establishments must accept cash as of November 2020
https://www.cbsnews.com/newyork/news/new-york-city-cash-law-...
https://www.cbsnews.com/newyork/news/new-york-city-cash-law-...
Tangentially, I'm also pleasantly surprised how easy it still is to buy a physical MetroCard. My understanding a few years back was that contactless payment would be the default by now and if I wanted to buy a physical MetroCard, I'd no longer be able to do that at stations but I would instead need to go to "select retail partners" to do so.
As a guy who used to have to take a zipper bag full of cash to the office safe every night, the convenience of the customer part may be laughable but the safety of the staff part isn't. Offhand I can't think of a more effective way to bring back 1990s mugging culture.