Megan McArdle wonders:

You can’t blame it all on lawsuits; my doctor didn’t test me for hyperthyroidism because she was afraid of the malpractice suit that would result from my losing too much weight and getting heart palpitations. Nor can you blame it on money; my doctor doesn’t profit from giving me blood tests that all come back normal. And I don’t think the lack of rational rationing can be the culprit either. To the extent that insurance companies have bad incentives, it should be to do too little, not too much. They should have incentives to ration this sort of thing, but they don’t.

I suspect the ultimate cause is the medical culture, which will make this sort of thing very hard to eradicate in either a single-payer or a private system.