Doctors, are the decision-makers in prescribing drugs. And to be fair, they often don't realize that to prescribe a brand-name drug often means switching from a generic that costs many times less. Costs are invisible to them. Which perversely means that the money that drug makers pump into the system has that much more power to sway their decisions. If they're constantly being cozied up to by drug makers pushing potentially spurious benefits, why wouldn't they prescribe those brand names?