USPO is a first class mail monopoly because other players choose not to get in that game. Instead, even when you do ship via another carrier if that carrier dee

USPO is a first class mail monopoly because other players choose not to get in that game. Instead, even when you do ship via another carrier if that carrier deems your route to be too unprofitable they will give it to the post office because they cannot refuse. In fact, FedEx and UPS are the post office's biggest customers for this very reason.