there are places where people actually have to check what their doctor is prescribing them? i know you're only using it as an example but i personally ran on the assumption that with my short-if-nonexistent list of known allergies available to them and the frivolous lawsuits people love to throw around with even the slightest fuckup they'd pick the best one for you. depending on who/where they are, they might go with most cost effective though.
Big pharma has big pockets, LS. It's not terribly unheard of for doctors to prescribe things that... really don't need to be prescribed. Beyond that, doctors often prescribe the most
expensive medicine, even if something else is as or nearly (and definitely
sufficient, many times) as effective (being fair, they do this as an attempt to
avoid lawsuits, but...). Plus there's just... other stuff. It's a mess, in a general sense. At least in the states. Second, third, etc. opinions are usually a good idea, if you can afford to get them.
Personally? I had to get a second surgery done because the first doctor that did it did something basically monumentally stupid (went ahead and closed the wound instead of leaving it open to heal -- which is what should have been done, and what happened the second round). A second opinion (or a couple) and a little research would have probably cut a good three months or so out of my bed-ridden period, several years back. Was a bit too young at the time, and not the one talking to the doctors (was back in high school, bleh), but... yeah.
As for the lawsuits, well. That tends to be for people that can afford legal fees. That's not very many people, all told, and there's definitely doctors out there that just run the numbers and decide the occasional lawsuit's worth the money on the net.