Across most of the world, Mastercard/Visa has used various threat tactics to basically tell merchants that if they charge a card fee they'll get banned from mastercard/visa.

Obviously for most businesses, thats a death knell, so most capitulate.

And the few places with competing payment methods (eg. Kaspi in Kazakhstan), Mastercard/Visa have ~zero fees, and sometimes even negative fees (eg. "special offer, you get half price use of the subway if you have a mastercard")

I don't think that is the reason cash has died.

Cash has died because it is inconvenient, unsanitary, and risky to walk around with large amounts of it.

When I pay cash it's because (a) I'm getting a discount (b) I want to be anonymous and not give any personal information (c) my credit card isn't working on their equipment (d) I'm giving tips and worried that their company will take some of it (e) I buying/selling used items from a stranger and want to use an irreversible method of money transfer. If it weren't for these reasons I wouldn't ever use cash. It's inconvenient.

(e) can be served by cryptocurrency, I suppose, but there are other issues with it, like the stranger being able to see your account balance and then come at you with the $5 wrench.