Patient: A week ago I felt something snap in my back, and it hurt so bad, I was ready to go get an MRI of it, but I managed to wait till this appointment.

Doctor (unbelievingly): Mhmmm?

Patient (in an aggrieved tone): It’s just that the insurance company won’t pay for an MRI like that, and I didn’t quite want to spend so much money.

Doctor (patiently): The fact is that MRIs are not useful for showing small transverse process fractures, which would be the most likely injury other than a muscle strain given your story. If a broken bone is suspected, an xray is still the best test.

Patient: (blank look)

Okay, folks? This is why it’s good for patients to have some share in the direct cost of healthcare! This is of course an extreme instance (what provider would give someone an MRI without a doctor’s order?), but you see the principle. Also you see why one goes to medical school, instead of being allowed to order and take what one pleases.