I think the USPS has the same problem that every business in America has--fewer people who want to work. 59 million in America on welfare, and the people in power in D.C. would rather spend money buying votes than upgrading an important government service. I live in a suburban city adjacent to Houston Texas. When we first moved here, I did the change of address form. I also went online and changed our address everywhere I could. A couple months after we moved, my wife was in a Target, and her Target card was declined. She had to go to the customer service to use her Visa card and still get the 5% discount (which was why we had a Target card in the first place.) Later I called Target customer service, and found out they sent a statement to the new address--which was absolutely correct including 9 digit zip--and it was returned "Addressee unknown." OK shame on Target who still had a valid phone and email on file.
Next, my wife and I applied for vote by mail. Those are, of course, separate applications for each registered voter. No word back. Since neither of us received mail ballots, I went to vote in person in the next election. Flagged as a vote by mail voter, in order to vote, I had to fill out a lengthy form explaining why I didn't vote by mail (no ballot received) and was informed that if the mail ballot showed up, I would have to go to the courthouse (downtown Houston) to contest the mailed-in ballot. Fortunately, I didn't have to do that, and shortly after the election, we both filled out the forms to cancel vote by mail.
OTOH, in the six years we've been here now, we've never failed to receive a parcel sent by USPS or a package turned over to USPS by UPS or Amazon (I don't really know how that works...do they hand over packages to USPS for final delivery, or to they have access to the cluster boxes directly?) I have, however, had damaged packages from both UPS and FedEx.
BTW, Target had an opportunity to turn a USPS mistake into a customer relations opportunity but did not. We almost never shop at Target in the last six years, for various reasons, but we do get 5% cash back from Amazon with our Amazon/Chase Visa card.