Just going from my own personal experiences, if I were to compare USPS to competitive delivery, ie: UPS, FedEx, Amazon, etc., I would say, without a doubt that USPS is as good, and probably better, than the competition.
Now, in regards to competency v. cost, I couldn't say because I don't know. I mean, I think USPS is great, but if it takes a zillion dollars to make it that way, that is worth looking in to in my opinion.
But I have been using USPS for my personal and business mail delivery and I would say USPS bats about a .995. I can't say that about the competitiors. I do have to use UPS, FedEx, etc., on occasion and I really have no complaints there but there have been incidences, delays, times I missed the delivery driver and I had to go to their facilities to pick things up. That wasn't too cool. But when you consider my volume of mail, and the number of times mail/USPS/FedEX, etc., has dropped the ball, it's not even a flea on an elephant's ass. I think USPS screwed up once in 14 years. And even that was no real biggee. My mail got delivered next door. The neighbor dropped it off. That's a pretty good record.
I give USPS 5 out of 5 stars.
But some of the people I know who work there are bat**** crazy. LOL! (Love 'em anyway.)