USPS is only in business because Congress writes them a check once a year to cover the money they hemorrhage. Their problem isn't your local mail carrier, it's the system set in place that relies on government funding of a private company to operate. FedEx, UPS, etc., would all have gone under a very long time ago if they operated the same way. Handguns are required to be shipped next day air because it reduces employee theft. Their system is archaic, but there is no need to update because the friendly taxpayer subsidizes their losses and inefficiency. Just for example, I regularly order bagpipe reeds from a manufacturer in Champion, Oh. That's 25 minutes from my house, but he sells only mail order. The package goes from his shop to the USPS hub in Warrendale, Pa. I've had packages sit at that hub for weeks before making it on a truck. Then it comes back to Ohio and processed through Youngstown one hour from my house, then Ravenna, finally the same county, then out for delivery. Such a poor business model is sustainable only when the public is being soaked to fund it.
The ONLY reason USPS is the carriers mandated in certain circumstances is due to federal contract and subsidy. UPS or Fed Ex could ship much faster, cheaper and with fewer incidents than the U.S. Postal Service.