What annoys me is when people have a credit account with businesses and then use a credit card to pay that off on the 20th. That is an obscene practice that I am amazed that places will allow. IMO once you have had the businesses credit you have no right to expect them to also pay a merchant fee on the settlement of that amount.
But I also would support a cash handling fee for people that pay large purchases with cash, since that has signifigant risk to businesses compared to either eftpos or credit card transactions.