In short, because of our culture. And it's costing us big time. Conclusion of the article:

http://www.jlgh.org/Past-Issues/Volume-6---Issue-2/Editor-s-Desk---Free-Market-in-Health-Care.aspxOur system of health care is costly, inefficient, and cumbersome to access. We accept these flaws because the system is consistent with our cultural bias of rugged individualism that considers individual choice as an absolute good. However, even this characteristic of our system is often merely an illusion. (Most of this Journal’s readers are physicians who know how to access the system, and which choices to make, so we are not acutely sensitive to the problems faced by lay consumers of health care who must gain access and make choices.)

Since the resources available for health care will not remain forever unlimited, we will soon have to make choices as a society that will outweigh the patient’s choices. Doing so will require not a change in technology, but a change in culture.