That's where most of it comes from in the US, interchange rates on credit cards are not regulated, so they're generally somewhere around 2%. Which, coincidenta

That's where most of it comes from in the US, interchange rates on credit cards are not regulated, so they're generally somewhere around 2%. Which, coincidentally, is the benchmark for "decent" credit card rewards. Some cards will offer rewards on certain kinds of purchases, often up to 5%, but offering only 1%, or nothing for other purposes. Since the average person only has a single credit card, the majority of cardholders produce more in interchange fees than they collect in rewards. There's also some complicated accounting voodoo that I don't truly understand, that effectively means that banks can treat extended credit as a pseudo asset, plus, whenever alone is outstanding, it's value is added to the virtual money supply. It is possible for an individual customer to get significantly more in rewards than interchange, but as this is a relatively small portion of customers, most issuers do not seem to care.