In the Nordic countries, you can certainly pay admittance to a club and shop in a thrift shop with a card. You can pay by bank transfer done with a phone app (MobilePay in Denmark, Swish in Sweden, etc) at a garage sale. At the last garage sale I went to, there wasn't anyone around -- just a sign saying everything was priced, and to transfer the money to 12 34 56 78 with MobilePay.

In fact, trying to pay cash can cause problems -- so many people use the electronic methods, the doorman might not have any change. (This is often the case at the weird gigs I go to, where only 25 people attend anyway, and it barely breaks even for the promoter).

I've heard of a trial to donate money to the homeless using a card, but it was only a trial. It's not normal to tip in a restaurant (or anywhere else).

However, the post spoke of having to buy illegal alcohol at college, so the person is clearly in America. But there are always queues at the cash machines near Christiania in Copenhagen, where everyone goes to buy weed. That's the only remaining thing Danes use cash for...