Most doctors dont have the types of antibiotics memorized by heart either unless they work in a specialty or ER. There are cell wall destroyers, folic acid synthesis interruptors, protein synthesis disruptors, etc. [1]
Gone are the days where a doctor should be taken at his judgment 100% as if medicine is a black box enigma. The average HNer would be wise to google about their conditions and drugs they consume. A doctor can only remember so much - they are primarily valuable for their experience in hueristic diagnosis -- not for knowing everything medical and everything pharmacutical. It is wise to relinquish some responsibility to a professional but not all.
Most of medicine aside from surgical methods can be understood by a mildly intelligent person who cares enough, because of wikipedia and google, everything except actual experience is very accessible.
I dont see how your astonishment is anything other than misinformed hyperbole.
[1] https://upload.wikimedia.org/wikipedia/commons/8/87/Antibiot...