Visa has $10.4 billion in revenue off of processing $4.4 trillion in transactions; that seems to make the credit card tax a mere 0.2%, which is off by an order of magnitude from the conventional-wisdom "credit card tax". Where does this mis-match come from? Is the revenue hidden, and Visa is taking in a few hundred billion in revenue? Or is the revenue potential just much smaller than conventional wisdom says? (eg, the 2-3% and $X trillion come from different classes of transactions, and shouldn't be combined.)