You're equating not-done-in-the-market with unnecessary. Public goods are hard to fund via markets -- for instance, if the U.S. military vanished tomorrow I don

You're equating not-done-in-the-market with unnecessary. Public goods are hard to fund via markets -- for instance, if the U.S. military vanished tomorrow I don't think it'd be replaced by corporations competing to sign you up for defense against invasions by offering the best service at the lowest price. (This also shows a downside of governments providing public goods: we in the U.S. are buying way more "defense" than optimal.)