I ship a lot of packages by USPS. the local post office where I go, the folks are great. always friendly and always helpful. Private industry would never agree to deliver a letter, anywhere that has a mail box, for 49 cents. Think about the magnitude of accomplishing that on a daily basis. And, yes, the postal service is supported primarily by the revenue they bring in.
once paid UPS to next day some event tickets to my sister inlaw. Tickets arrived two days after the event. Their response, sorry, tough, no refund.