The US does not have an "ultra-capitalist" healthcare system. Its healthcare system is heavily regulated and subsidized and many of those regulations are bought and paid for by the incumbents to prevent competition, i.e. the thing that allows private systems to be efficient. You can't just call something "capitalism" while regulating it into market concentration and expect that to work.

You're making a "no true Scotsman" argument. This is, in fact, how capitalism works whenever you fail to regulate it. Rent-seeking and regulatory capture is a feature, not a bug.