Not sure if matters but at least to my understanding, DanKort is a debit card, so I would expect it to have a flat rate since the cost of transaction is less dependent on the total amount vs a credit card transaction where there is more clearance and risk involved?

At least in some jurisdictions I lived, debit card is as good as cash (well, not exactly the same but because handling cash has also its cost, most of retailers treat them equally)