Let me add a bit to the discussion. The Post office tries to operate on a three year cycle. Basically they make a profit the first year, break even the second year and then lose money (burn the surplus from the first year) the third year. Then the govenrmet decides that they can run it better so they tell the PO they can't have a big enough increase to do the three year bit. So you wind up with these one cent increases all the time. Oh, and don't forget, congress gets to buy votes by telling the PO they have to give discounted rates to all kinds of groups (below cost).
I suspect the PO has a few more stores (Post Offices) than any of the other carriers. Just listen to the outcry if the PO tries to close an office that doesn't make good business sense.
They also move faster than a lot of the other carriers. I've ordered some MB parts in the past few months and tracked their progress to my house from the left coast and from Texas. They did fairly well in their trip until they got to Chicago. Then they enjoyed the weekend sitting there. Taking in the sights of the city, I guess. The PO has a policy of packages having a 20 hour or less turnaround time from the moment a package enters the grounds of the Bulk mail center to leaving the property. They ran two shifts a day when I was there and ran 22 hours a day during the Christmas rush.
As pointed out above, they will come to YOUR house and pick up a letter to your aunt Tillie and deliver it to her in BUFU, KY (I am actually trying to move there soon). And do it for 41 cents. I'm not sure most of you would get up off the couch and walk to the mailbox for 41 cents. (I probably wouldn't).
My biggest gripe with them is that they don't raise the price in 5 cent increments (of course they aren't allowed). At least we would not have to fool with all the blasted change when we buy stamps.