We need a government run post office because the free flow of information to the voting public is vital to a republic and a government PO can be forced to be neutral and obey the 1stA.
Think about a PO controlled by Bezos or @Jack etc.
I think the PO should be updated to include web services like email, site hosting and DNS registration etc.
Plus the USPS is mentioned in the Constitution iirc. Okay, here’s what I could find. Article 1, Section 8:
“To establish Post Offices and Post roads”;
That’s all I could find. Everything else is summaries, opinions and whatnot.