What are so many doctors lacking nutrition knowledge?

I get something similar in my job working with investments and people are usually surprised or mad that I can’t give them tax advice. I’m a broker, not a CPA, just because we both deal with money doesn’t mean we both know the same things.

My wife is finishing up her MD of Pharmacy(or pharmacology I guess?) and she had not had any nutrition courses outside of some basics in undergrad. Nutritionists are responsible for nutrition