The biggest chunk of waste is from unnecessary medical tests, procedures, drugs etc...
They really don't understand the nature of diagnosing problems, whether mechanical, electronic, or in the human body. Often it does involve exploring with tests possibilities that are not the cause of the problem. I work in electronics. Much of my time is spent devising and carrying out tests to determine the cause of problems, and sometimes replacing parts to see
if that fixes the problem. It's sort of analogous, except the human body is vastly more complex than a high voltage power supply for a microwave amplifier. Oh! And the equipment I work on can't sue me for millions of dollars - like th4 said, I don't need to perform tests for the sake of defensive medicine.

time!
A guy walks in to see his doctor, and says, "Doc, when I stand up quickly, I get a blinding headache that lasts for a second or two." Doctor orders a very expensive MRI.
Was this wasteful?His wife, several years later, complains to the same doctor of headaches centered in a certain part of her head that seem to be triggered by certain strong odors. Doctor orders a very expensive MRI.
Was this wasteful? Hypochondria? Insurance fraud?My MRI found a brain tumor (I know, explains a lot), and I had surgery 6 days later. My wife's MRI found ................. a brain tumor, and surgery was done soon after. Those MRIs could just as easily found nothing; another way of saying that, though, is that those MRIs could have just eliminated dangerous possibilities.
My point (I do have one)
is than "wasteful" is a very slippery term in this context, the meaning changing with hindsight and agenda.