Earlier quoted context omitted.
You have to differentiate common purchases from "large" purchases in this discussion. I'm certain you don't think there's something shady going on, or tax evasion happening, if someone uses cash in the grocery store or at Pressbyrån, or to pay for some little gadget or whatever at Kjell&Co. This is what people think of when someone "uses cash". Not hauling tens of thousands to buy a used car or to settle the bill for…
FWIW I am Australian and we have a similar adoption rate of cashless payments. If a merchant tries to promote cash options I immediately think they’re doing it for tax evasion reasons - not because of the touted reason that “card payments cost more to process” (they don’t once you factor in the cost of handling cash).
I don't know about Australia, but in New Zealand many small retailers and restaurants add a card payment surcharge (typically 1.5%-2.5%) automatically when you pay by card. So you are somewhat penalised for the convenience of using a card. This never happens in Europe.