I just saw this article which expresses something I've felt for a long time.... that most doctors look out for #1. Not that they're all "in it for the money", but it's certainly a factor for most.
I think this explains what happened when I went to my gp complaining of knee pain. He sent me to get an MRI (at a private MRI place, which billed the insurance company $6K- I got stuck with the deductible) and to see an orthopedist. So I get to the orthopedist and he's never seen the MRI and is able to tell what he needs to from a simple X-ray. So why the MRI that no one ever looked at? I'm thinking the MRI place might be giving doctors a little kick-back for referrals.
No wonder we're having a crisis with health insurance! (Okay, it's more than just that, but I seriously think overbilling and over-testing contributes to the problem).