A large portion of the folks I know in their 20s in NYC don't even carry cash anymore unless there's a specific need for it on a given day (taking a class that'

A large portion of the folks I know in their 20s in NYC don't even carry cash anymore unless there's a specific need for it on a given day (taking a class that's taught by an individual who takes cash, for example). Why worry about a bunch of pieces of paper or round metal discs when everything is a tap of your watch or phone away? I don't even use my metrocard anymore since the subway started using tap to pay.