I had a realization that the very existence of private domestic shippers in countries indicates a failure of their government to provide universal infrastructure needed by all citizens.
There may be specialized needs like same-day couriers, special handling requirements and other edge cases, but those should be small specialty houses, not international mega-corps.


Nothing about providing a nationalized service forbids you from using alternate means you find more suitable. That seems like a false premise to me.
Also, to your other point: What?? They had state-run mail as far back as the Persian Empire!
These don’t seem particularly compatible. According to you, the mere existence of an alternative is a government failure.
The existence of direct competitors to the government’s are indicative of, but not tantamount to a government failure, yes. If a tax-subsidized government service leaves so much room in the market that a direct, like-for-like competing business can profitably exist, it is hard to envision how that could be so without the government service being a failure in some way.
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?
My statement was qualified to include edge cases. If you want your product shipped with special care, or with special considerations like refrigeration, or in a time frame shorter than is expectable via bulk mail, then there would be plenty of market for those.
For standard shipping, it is less that I think there is a problem with private entities existing in the space, but that few, if any actually would exist if there was and had always been a national comparable alternative, like there are no non-municipal water services but theoretically could be if not for lack of demand.
But isn’t that describing the system we have now?
In the USA, USPS will ship any mail or parcels up to 70 lbs. Shipping heavier than that is an edge case which you’ve described. You can send anything via USPS, except for edge cases or if you want a special accommodation like sooner delivery.
That is true, but the market overlap between the USPS and, say, FedEx and UPS, is indicative of a failure of government in that arena, in my opinion.
The USPS service is tax subsidized and benefits from tax exemption and de facto huge economies of scale. The fact that those for-profit enterprises can compete on price at all in that direct like-for-like competition is dubious and indicative of a failure of the USPS to act per its national charter, as a public service.