Both Amazon and Fed ex have embarked on plans to deliver their own “last mile” package delivery previously contracted with the US Post Office. Here is a link to run75441 (postmaster Mark Jamison’s) piece on this process Fake News, Flawed Analysis, and Bogus Tweets from 2018 for a much more complete description. I have pulled a quote from the more recent Business Insider post on “last mile” delivery.
According to the US Postal Service Inspector General, the new requirement to pre-fund retiree benefits accounted for $55 billion of the agency’s $62 billion loss incurred between 2007 and 2016.
Because of that, the Postal Service can’t make the massive investments into its logistics networks that its competitors have been able to.