Two examples of structural problems with our health care systems:
1. We lead the world in transitioning from inpatient to outpatient care; for instance, I read a source last night that said the majority of hernia repairs in the NHS were inpatient, and the overwhelming majority of them in the US were outpatient. That's good, but an unintended consequence of it is that it's easier to route a patient to a surgical procedure if it's done outpatient, and as a consequence US patients get a lot more of these procedures, some of them (cardiac stents being a recent well-publicized example) of dubious utility. Our relative overconsumption of services doesn't lead to better outcomes, and thus represents misallocation.
2. Our health provider systems are more decentralized, delivered in smaller clinics and hospitals. Our hospitals generally, nationwide, have poor utilization. Not only do we therefore overspend on plant and salary costs (which we do, relative to Europe) but coupled with our price transparency problems we end up with the situation Atul Gawande described a year or two back, when he noted the insane difference in prices for an MRI at different imaging centers in a small region of (iirc) Texas.
Our system right now isn't good and some of it (but by no means all of it) is related to how we regulate the way it's funded. But Medicare overspends on many of the same things. The structural problems will need to be corrected no matter how we design the rest of the system.
Ultimately I think the problem in the US is a sort of perfect storm of badnesses.
(Good sources: Kauffman's health cost explorer, the McKinsey report, the Health Care Cost Institute annual breakdowns).