If you have any choice in how you are treated, you will make your best judgement based on information available to you, such as by the recommendation of a friend, or a Yelp review. This is the same process you use to make any important purchase.
Before you have work done on your car, do you fly to China to inspect the part factory? You don't, because the relatively low risk you perceive that these parts will fail doesn't justify the expense of travel.
Do you perceive low risk because a government agency put a stamp of approval on the part? Probably not. Most likely, your risk assessment is based on information you've gathered about the final product, the auto shop -- that it is well-reviewed, and that your mechanic seems knowledgeable.
Furthermore, only you really know your exact needs. An expensive high-performance car part might provide you some marginal benefit, but not so much benefit that you're willing to buy that part at the expense of something else that's important to you, like your electric bill. A race car or Uber driver might make a different decision and choose a different part to suit their needs.
Medicine is like car parts. Bad ones can kill. But through the free market, a system of feedback is established that tends toward a wider variety, and higher quality, of parts overall.
When politicians prioritize some drugs over others, they interfere with this system, and money is spent on drugs and research that people don't necessarily want or need. You can imagine race car drivers getting together and lobbying politicians to subsidize high performance parts. Because these subsidies are funded by taxes, money is effectively taken from individuals who might prefer a different part. Now, those individuals who are not race car drivers have less purchasing power, and fewer choices overall.
You're correct that this is more or less the libertarian perspective, but I find it in no way extreme. I find it principled, direct, and humane. In our society, where nearly everyone has a smart phone and may conduct research at any time, I can't imagine a more effective system. I'm sure it was much easier to criticize the free market in a time when people couldn't read, or didn't have a global information database accessible on their person at every waking moment.