Passed by a Republican-led Congress and signed into law by President George W. Bush, the PAEA gave the Postal Service new accounting and funding rules for its retiree pension and health benefits. Up until 2006, the USPS funded those obligations on a pay-as-you-go-basis, pulling out of its pension fund and adding to it as retirees' costs came in. But the PAEA required the Postal Service to calculate all of its likely pension costs over the next 75 years, and then sock away enough money between 2007 and 2016 to cover most of them.

 

https://theweek.com/articles/767184/how-george-bush-broke-post-office

 

They were set up to operate like a business but never followed careful accounting rules so now if they want to fold up shop or become a real business, the choice is theirs.