Why are US health care costs so high?

I just started reading Maggie Mahar’s Money-Driven Medicine: The real reason health care costs so much.
The US spends almost twice as much as Japan on health care, but the Japanese live longer and have a lower infant mortality rate.
Why is health care so expensive in the US? Is it because Americans have access to all the health services they want, including elective surgery? In developed countries where the government limits health care resources, patients can wait months for elective surgery. There are 15 procedures that generate the majority of waiting lists in Canada, the UK, and Australia. Those procedures account for only 3 percent of US health care spending. So that’s not it.
Is it the number of hospital beds, doctors, and CT scanners? Compared to other developed countries in the OECD , the US is below average in both the number of doctors per capita and the number of CT scanners. When you compare beds per capita, the US is in the bottom 25 percent. So it’s not that.
Is it the high cost of malpractice insurance? Malpractice payments account for less than 0.5 percent of health spending. But could it be the unnecessary tests and procedures doctors order to protect themselves in the event of a lawsuit? It’s very difficult to say whether a doctor orders a specific test solely because he believes it is in the patient’s best interest. But other countries with lower health care costs also have malpractice claims, so there’s no reason to assume the US is the only country where doctors practice defensive medicine.
According to Mahar, the reason for rising health care costs in the US has nothing to do with the individual components we single out for blame. It’s a matter of larger economic forces.
“Put simply, over the past 25 years, power in our health care system has shifted from the physician to the corporation. A professional, the physician pledged to put his patients’ interests ahead of his own financial interests. The corporation, by contrast, is legally bound to put its shareholders’ interests first. Thus, many decisions about how to allocate health care dollars have become marketing decisions. Drugmakers, device makers, and insurers decide which products to develop based not on what patients need, but on what their marketers tell them will sell – and produce the highest profit.”