Why don't doctors do that? Shouldn't doctors know what the available drugs are to treat a disease?
And I know for a fact that sometimes pharmacists will give you a different size pill than the doctor requests, if it's substantially cheaper. They tell people to just break them in half, or take 2, or whatever.
Doctors do know the available drugs. . . but the current system is set up such that the primary channel for learning about them is direct-to-physician marketing by drug companies.
Which is hardly the most effective channel. In fact, studies have shown an inverse correlation between how much time a physician spends being "educated" by drug reps, and patient outcomes. Of course, while the patients' quality of care goes down the cost of care goes up, because they're paying out the nose for expensive new drugs instead of equivalent (or, as is often the case, superior) generics.
And I know for a fact that sometimes pharmacists will give you a different size pill than the doctor requests, if it's substantially cheaper. They tell people to just break them in half, or take 2, or whatever.