Your argument that people with good credit pay less to use the network is sound, and in that sense it almost constitutes a minor poverty trap. But to call it taxation ignored all of the remarkable innovations that the card brands have made. They have successfully managed to connect nearly all of the worlds banks together in a way that facilitates almost instantaneous payments between them. Sure this innovation is old, but that doesn’t make it any less valuable to consumers. It’s still so valuable today, that a lot of our modern day payment innovations are still based on those very networks. Try and think back to a time before payment brand networks, and how tedious payments were then (especially international one) before dismissing the value of the card brands.