the very existence of private domestic shippers in countries indicates a failure of their government to provide universal infrastructure needed by all citizens.

Nothing about providing a nationalized service forbids you from using alternate means you find more suitable. That seems like a false premise to me.

These don't seem particularly compatible. According to you, the mere existence of an alternative is a government failure.

They had state-run mail in very powerful states with lots of resources like the Persian and Roman empires, but those instances were few and far between. Like I said, postal services did not become widespread until the 18th century.

But you yourself in your post said "domestic shippers should not exist." So is your point that national postal services should be better, or that private ones shouldn't exist at all?

Funny how you simply ignored your own misunderstanding of the history of nationalized postal service.

You don't even know the history.

Also you just contradicted your own claim that private shippers shouldn't exist.