making the shops pay more to use the payment service, so that the shops then increase the prices, so that you pay the same as before

Just nitpicking because I enjoy these thoughts:

When the shop increases prices, it has to do it for all the customers, including the ones without credit card. So a part of the cost is offloaded to other types of customers. While credit card customers should see a slight increase in price, it should not be as much as they saved previously. So still a net win for them, at the cost of others.

As others pointed out, the real scheme is probably entirely different.