I have worked for the USPS on three different occasions. I drop off my packages at the facility I worked at twice. Complete incompetence is the standard. My dad is a retired mail carrier. I know a lot of postal workers. Most are drunks, most incompetent. And the sad part is it is getting worse.
My own postal carrier is a useless $%^&. A couple of times I had packages returned to me after a month postage due. (smart post by fedex makes this possible) He writes out the nobody was home slip in his truck, puts the slip in the door rings the doorbell and runs back to his truck.
I have gotten to know my neighbor a block over because usually a few times a week I am walking over mail, she does the same for me.
Incompetence is the standard because they can't get fired and to bury the worst employees they promote them to supervisors. So you find the most useless carrier you can and knowing you can't fire them you instead promote them so hopefully their replacement can actually deliver the mail.
New carriers who know how the system works, pass their 90 days, then claim they got hurt and are put on light duty. They basically sit on their asses all day misorting mail cause they really don't care, they can't get fired.
Now the scary part for all us ebayers. When sorting packages, there would be a gurney for every route (like a big laundry gurneys on wheels) To be most efficient they would play basketpackage with anything they could toss into the gurneys so they didn't have to walk over and put it in. I worked in a post office with around 50 routes, the gurneys in the back were easily 30 feet away. Sometimes they would miss and the package lands on the floor, other times they miss and it lands in the wrong gurney. Sometimes they would put it in the right gurney sometimes not.
Now the worst thing that can happen to your mail is it is missent. This enrages you average postal worker because that individual just got more work because of somebody else's screwup. And they usually take that anger out on your package or mail.
I overpack everything I send. I think I have only had one damaged item in the last 2 years. Basically I pack my stuff so it will bounce if dropped or thrown.