The universal service commitment makes possible the provision of regular mail delivery to relatively isolated rural locations. If the Postal Service were an unregulated, profit-making concern, mail delivery would cost a premium for customers in such areas. That is why, when push comes to shove, you can find conservative members of Congress from rural districts sticking up for their relatively costly local post offices and mail routes.
...
The point here is that the spurious notion that the U.S. Postal Service should be financially self-sufficient — which goes back decades — helped give rise to the ability of Trump’s crony in charge of the Post Office, the conflict-of-interest-ridden Louis DeJoy, to cut services in the name of accounting solvency. For his part, Trump has acknowledged openly that his refusal to provide necessary supplementary funds to ensure effective delivery of the mail is founded on his determination to frustrate the vote-by-mail system.
In my many decades of living in the US, the post office has always worked pretty well. But it's also visibly obvious (everything looks like shit) that it's always been run with the smallest amount of funding any congress thought they could get away with.