Many doctors have textbook knowledge and some knowledge through their patients, but my sub doctor has said some things that I knew were false or he didn't understand. I do think he generally cared though. Taking a drug and withdrawing from it is the best (and the worst) way to learn.
Yea, I've often been really caught off guard by the limited nature of my prrescribers' pharmacology knowledge. I've had many MD's make what would seem like really fundamental mistakes with medication that is commonly prescribed. I had my PsyD tell me that Pregabalin (Lyrica) exerted its effects in the same way that Alcohol and Benzodiazepines do. It's not like this is coming from out of left field. These drugs all exert their effects in one way or another surrounding the GABA neurotransmitter, but it's pretty common knowledge that any idiot could find by reading a wikipedia article that Pregabalin and Gabapentinoids exert their effects through a completely different mechanism than the above stated drugs.
This would seem like a "who really cares?" type of situation, but my PsyD's limited knowledge came to bite me in the ass when I ended up re-entering a Methadone program and was told that the Pregabalin that I had been taking for months had the same potential to cause death when combined with Methadone as Benzodiazepines, which are a well known Grim Reaper of sorts for MMT patients. So, because I failed to correct him when I should've, my argument sounded more like the ravings of someone now wanting to get "cut off".
It's always been a crazy phenomenon to me, that is, the limited knowledge of some MD's. How can they go through so many years of intense study, medical school, internship, residency blah, blah, blah and then not have the time to read a simple Wikipedia article regarding some of the drugs that they have probably prescribed hundreds of times. I mean, the knowledge that I and my peers have acquired regarding drug use has been done in our "free time". It's not like this is even my job, but I constantly find myself being flabbergasted by the limited knowledge of some MD's. It's a thing, so don't feel extremely surprised when your Doctor makes what seems like a totally fundamental error with your medication.
Also, if your prescriber say, prescribes you a potentially dangerous combination of medication (that could, you know, kill you), it's like "oops, my bad". When you, as an addict make a mistake, the hammer comes crashing down.