That says more about the way the company does corporate accounting than its business model. Microsoft also has roughly the same reported margin -- does that mean that there's a lot of margin for the taking with Microsoft? No. You're taking a noisy signal and putting meaning into it which isn't there.

Again, the networks take a small fraction of the overall fee, and the vast majority go to entities outside of the card network itself. Take a look at how the merchant discount rate breaks down, and you'll see who the true takers of those processing fees are.