In Norway there is already a low fee processor called BankAxept. It has made it practical for shops to sell even the cheapest item and accept payment by card without losing money.

https://en.wikipedia.org/wiki/BankAxept

This seems to have happened in the UK now too, though all bank debit cards have been Visa Debit since 2009 or so. I think fees are now solely percentage based and close enough to bank cash handling fees that there's no longer any downside to accepting card payments for small transactions.