When Jeff Bezos starts out competing the interstate with his private roads, then you can make that argument. The fact is that roads serve their market well, and if the USPS did the same they would not be being out competed by 10 different private entities at once.

I don't care if it's not their fault or that their hands are tied by regulations. The mere fact that they are in trouble is evidence that they aren't serving their purpose in their current form.