I agree with it when it comes to the USPS, but also think you could substitute the word "library" for "post office" and have it be equally true.
What the critics of the Postal Service forget is that it was never intended to be a money-maker. In fact, the post office has always operated with public money in order to perform a public service grounded in two democratic aspirations: first, providing the same service at the same affordable price for every citizen — right now an economical 44 cents for a first-class letter.
As the nation becomes more diverse and the gap between the rich and the poor widens, our interest in the unifying and leveling effects of institutions like the post office may recede, as well. That, combined with the technological shift, predicts the regrettable decline of the post office, an institution deeply symbolic of our best democratic aspirations.