Thrilling, I know, but here’s the fact pattern that drove the discussion anyway:
1. The U.S. government, or organs thereof, commonly preaches free and open markets to the rest of the world.
2. The U.S. market for the delivery of “letter” mail (i.e. excluding packages) is subject to statutory monopolies both for delivery of certain types of mail and for access to consumer mailboxes, though there is considerable private provision of mailing services upstream of the delivery function.
3. U.S. postal regulation also until recently involved cost-of-service regulation that Some regarded as highly litigious.
4. The U.S. Postal Service provides its letter mail services at low cost and/or low price compared to nearly every other world postal administration. (Possible exception regarding the latter, IIRC, the New Zealand post.)