I've done it before at a doctor. "Here is the latest drug!!". "Can we start with a generic?", "Sure".
My co-pay just went from $50 per month to $5.
I work with a lot of doctors, they don't think it's their job to save patients money. They'll do it if asked though.
Isn't it simply a matter of asking, "Is there a generic for this, doc?"
Both $10 and $100 are greater than $0, the patient almost certainly always wants $0, and a doctor can do that math without referring to your plan.
Or is this a case of this particular method being combined with N other methods such that the doctor has trouble getting the correct information to the patient?
Edit: By $0 I mean "$0 more than the cheapest generic." :)