Market forces are great, but should be ignored in key sectors that are important for national security. That goes for rare earth minerals or shipbuilding or key supplies for munitions or PPE that we needed during the pandemic, (etc.)
National security considerations can adapt to market forces by either directly subsidizing the domestic product (so that it will be as cheap as the foreign product) or establishing tariffs on the foreign product (so that it will be at least as expensive as the domestic product) or by outright banning the import of the foreign product (so that only the domestic product competes in the domestic market).
Market forces aren't real. They are artificial arbitrary rules agreed upon by a majority of participants in a financial system.
They are not natural laws like Newton's law of universal gravitation and the fact that even one person thinks they are is the greatest scam ever pulled on humanity.
Humanity will never be free until it rids itself of economists and MBAs.
There are uncountably many examples of humans, presumably normal, existing outside of the rules set by free market capitalism and not collapsing into a black hole.
One such example is the Indigenous peoples of Australia, who lived for tens of thousands more years than the concept of free market capitalism has existed, without even the concept of money or property beyond what one carried on their person.
I have to assume that they are "normal" humans.
Even today many aboriginals struggle with "tHe NaTuRaL LaWz of tEh MaRkEt JuSt LiKe GrAvItY BrAh TrUsT Me BrAHHHHH" because they've only been exposed to them for less than 0.3% of their culture's total existence.
There are examples, today, right now, this very minute, in (extremely northern) Europe of presumably normal humans who look at the rules you consider to be "natural" with shock and horror.
A cult has convinced you that their ideology is natural law. You can both participate in this system and realize that it is all bullshit and not be a hypocrite.
- USPS - literally written into the Constitution
- Passenger rail - Amtrak keeps pudding along even though financially it doesn’t make sense.
- Merchant marines - cargo is cheap. And cheaper in flag countries with lax labor rules. Yet, we maintain a expensive flotilla.
Other than that, as you said, the USPS is supposed to earn enough to pay for itself, which means that mail in cities tends to subsidize rural services.
Do USPS or other mail services in the US have pricing that depends on location? In Poland where I live (much smaller, more uniformly populated and not federal country), I've seen no such things. The prices are the same everywhere, so it seems to me that in every private, commercial mail service the cities kinda subsidize the rural areas.
UPS and FedEx and some of the other private shipping services have much more fine-grained pricing based on where something is going. This means that if you are Amazon, it is generally cheaper to send packages to cities by private carrier and cheaper to send to rural areas by USPS.
That's absolutely not true and anyone who has been involved in sourcing knows this.
There are plenty of other factors other than price alone. Reliability of source, quality, ability to response to changing volume demands, reputation, customer service, sustainability, overall capability, regulatory compliance, IP protection, financial health, quality management systems, etc.
It's the reason why any large corporation has a months long supplier due diligence process.