“The typical transaction rhymes with "I’ll sell you $40 worth of paper for $43, with a few minutes of operator attention being required every several hundred transactions."”
An ATM costs a few thousand dollars. The money is in floating the cash, because the operator gets paid by the network days after you walk away with it. MasterCard bought Cirrus, a network that started as six banks, for $40 million. The machine sells paper. The network collects a toll on every sale, and that is the real business.