Moreso than that: there's a fundamental break from free market assumptions in that use decisions and cost decisions are divorced. Health care recipients (patients) and primary providers (doctors/medical personnel, though to a lesser extent facilities which are more aware of costs) don't bear and/or often don't know the costs associated with a given therapy or intervention. Instead, these are born by and/or negotiated by insurance providers. Even at a given facility, compensation rates for a given therapy can vary widely by insurance carrier, or even by plan within a given carrier.

More broadly, this is a problem at other areas of what we consider to be "free market" economies. Healthcare and defense are classic instances, but many group-negotiated services (utility contracts, broadcast media, "free" online services, even Microsoft's software sales channel (mostly OEMs and corporate site licenses, not individual end-users) violate base assumptions of free market economics.

While microeconomics is hugely useful describing behaviors in which it applies, I'm increasingly coming to believe that only a small fraction of what we consider to be free market activity in fact meets the core assumptions.

But yes: US healthcare is hugely inefficient.