If it’s a competitive market, we’d expect it to have certain characteristics, such as that: other things equal, a lower price means more demand; producers compete to offer the product at the lowest price they can; and the price mechanism promotes efficiency by guiding resources to their best use. In practice, no market will meet those conditions perfectly.
But the card-payments market has some particular qualities that make it very different from the stylised description I’ve just given. First, the card payments market is subject to network externalities, which is another way of saying that the cost-benefit decisions made by the various players are highly interdependent.