I used to think it was the consumer/cash buyer but it's pretty clear now that the merchants do not have the pricing power to pass these costs on. It's why they

I used to think it was the consumer/cash buyer but it's pretty clear now that the merchants do not have the pricing power to pass these costs on. It's why they get upset and try to lower fees. It's why Costco stopped taking Amex. If they could simply pass it on they'd be indifferent. There are various studies online confirming this.