Trying to ELI5 this to myself - USPS has to fund their pensions and is forced to keep money aside for it. They are unable to make price increases to account for all this extra money that they have to keep aside since they are a public service. Their competitors UPS, FedEx are not being held to the same standard, and so USPS is losing out? And this makes a convenient excuse to show USPS as a failed org?