My preferred Caltex does this (although it's a Starmart-triple dippable with Myerone, WISH card and EDR) . You can get round the charge by buying a WISH giftcard with your Amex at WW as they should take these
They used to have signs on the pumps a while ago stating that they didn't take WISH gift cards, but not sure if that's still the case. I walk past the place quite often so will have a look next time.