It is mainly if it comes to math teachers, most others have anseering books and stopped thinking themselves it's why they cannot answer questions and will not try to answer the question themselves.
That is sad, a teacher without knowledge and the will to learn daily, to discover and try out something new.

Too many people are labelled as idiots, not able to learn by a system that doesn't care about those who dare to think out of the box or just differently. If you do not fit in the system, do not understand what is asked you are out. :(