Random-- another comment related to cause and effect. It could be that all m.d.s are motivated solely by profit and that's why x% of all procedures are not really needed. Or, maybe the m.d.s are running the un-needed tests anyways to avoid liability when the patient eventually dies?
Its not just medical tests though. C-sections and hysterectomies have been way more common in the US than statistics in other countries would dictate, tonsilectomy rates can vary wildly from town to town and doctor to doctor, there seems to be a great deal of back surgery going on that is unneeded and dangerous, etc.
The problem is that a doctor might look at any one of these procedures performed on a particular person and say that that makes sense for that patient, but when you look at the statistics as a whole, there is something seriously, seriously wrong.
It doesn't even need to be greed. Entirely possible that a doctor will perform a procedure thinking that it is in the best interests of the patient, when he would not have if he was busier. I find myself giving more in-depth assistance over the phone at work when it is slow than when I am busy. No real malevolence on my part, just the way it is.