YMMV, but I still carry cash and find no inconvenience in this. Cash is never out of battery, never out of software support, and unaffected by AWS outages, cellular outages, or electricity outages. I also don't install apps that are supposed to make life convenient for others but not me. WRT that hairdresser chain, I suppose I'd simply use a different hairdresser that would accept both walk-ins and cash, and I'd hope there's no shortage of such.