Consider what happens when a new drug or other therapy becomes available. Let's assume that the new therapy is more effective in some cases than existing therapies - that is, it isn't just a me-too drug that duplicates what we already have - but that the advantage isn't overwhelming. On the other hand, it's a lot more expensive than current treatments. Who decides whether patients receive the new therapy?
We've traditionally relied on doctors to make such decisions. But the rise of medical technology means that there are far more ways to spend money on health care than there were in the past. This makes so-called "flat of the curve" medicine, in which doctors call for every procedure that might be of medical benefit, increasingly expensive.
Moreover, the high-technology nature of modern medical spending has given rise to a powerful medical-industrial complex that seeks to influence doctors' decisions. Let's hope that extreme cases like the one reported in The Times a few months ago, in which surgeons systematically used the devices of companies that paid them consulting fees, are exceptions. Still, the drug companies in particular spend more marketing their products to doctors than they do developing those products in the first place. They wouldn't do that if doctors were immune to persuasion.
So if costs are to be controlled, someone has to act as a referee on doctors' medical decisions. During the 1990's it seemed, briefly, as if private H.M.O.'s could play that role. But then there was a public backlash. It turns out that even in America, with its faith in the free market, people don't trust for-profit corporations to make decisions about their health.