The card PoS's come in two forms; one that only takes the Danish Dankort (which is the cheaper) and one that also accepts foreign cards.
Which is why merchants in Denmark - at least smaller ones - are still weary about upgrading to the fancy PoS, and therefore need to accept cash some times. Sure, there are alternatives to that, like MobilePay. But usually your problem will be with tourists, who don't have access to that, nor access to a Danish card, and can only pay cash. (Another good reason why governments won't abandon cash; they'd lose a lot of tourists too.)
I don't know whether PoS's are cheaper in Sweden than in Denmark, but generally speaking, Danes and Swedes have about the same level of trust in government, yet there are far more cash transactions in Denmark compared to Sweden.
And yes, there is Swish/MobilePay, but that only really works if you're local. A tourist - even one from a neighbouring country - will not have access to that.
There were iZettles in many Helsinki cafés a few years ago, but it seems to me that most of them have been replaced by normal PoS terminals.
Costs per transaction are higher but for really small scale the ease of use wins.
Source: Used to work as a technician fixing payment terminals.
Also, the Denmark-only Dankort is dying and its demise is happening fast: they are coupled as Dankort/Visa cards and the POS might decide to prefer Dankort but accepts Visa just as well. Neither Google Pay nor Fitbit Pay support Dankort and I have not seen transactions fail that would work with my Dankort.
Also, cash transactions are pretty rare too. Even older people use contactless, I have never seen cashiers have to pick coins from someone's hand as is customary with older people in Germany. Sometimes days pass without me seeing anyone pay with cash. In my experience the main source of cash transactions are German tourists.
Just like Hugo Boss don't mention their Nazi Uniform Design Division in investor calls.
Governments. We didn't stop making lists after 45, in neither the FRG nor the GDR, the outcomes were just not as severe if you ended up on one of them.