We don't ship via the USPS, but I used to work there as a temp holiday season employee for three months about 20 years ago. I can only say for the location I worked at (Omaha, NE main Downtown hub). From what I observed the USPS is beyond repair. Back then it felt like it was easier to scrap the whole thing and build a new one.

I remember they installed a couple of years prior my tenure there a brand new conveyor belt/sorting system throughout the entire building. That thing would break down every hour or so. Boxes would start piling up and crashing each other like cars on the interstate during a bad snow storm. The thing was very expensive and super glitchy. Instead of making the contractor to fix it, they hired them as full-time mechanics. There were always at least two of them at the building and all they did was resetting the controller computers and telling people to move the boxes manually off the lines in preparation for a reset. Reset every hour. One of them shared his salary with me during lunch. It was astonishing 20 years ago and it's still astonishing even now.

Another thing I noticed is how permanent employees acted. They did not care about anything at all, except two things: working as little as possible and getting paid as much as possible. I was a temp and there was a group of us. We worked fast, but nothing outrageous (not like Amazon warehouse pickers). Perms would often come to us and tell us to slow down because their super might get evil on them. They told us that the amount of volume we did in 2-3 hours usually equates to what they do in 3 days and they wanted to keep it that way. They didn't want their managers to think that their job could be done faster. And they were constantly filing grievances with their union and management about hours that temps took away from them. Basically, they could sit at home during a holiday or weekend and then file a grievance, claiming that the USPS did not offer them to work, hiring temps instead. And they would get 3.5 times their regular salary if such grievances involved holidays. Some of them joked that we, temps, just paid for his family's Christmas presents while he was watching football at home.

I have no sympathy for the USPS because of how their system operates. I realize there are plenty of hard working USPS employees, especially foot soldiers like carriers. It's a hard work. I wouldn't want them to get hurt by possible upcoming changes. But everything else I saw at the USPS back then has to change.