Our healthcare system, to the extent that it was intentionally designed at all, implicitly prioritizes consumer choice and immediate access over cost efficiency. While there are certainly gaps in access and affordability, the typical middle-class voter can still get elective care quickly from a variety of local providers. Most other developed countries have longer queues or certain services are less available. We also subsidize drug development costs for the rest of the world. Whether those are good reasons for paying more is a matter of opinion.
Of course there's also a certain amount of waste, fraud, and abuse that inflate our costs.