Most obey the rules. Few if any do not know what the rules are. Now, in the language we speak, few know what the rules are. They don't know, I suggest, for at least three very good reasons. One, as a society we are reading less and less and are more and more verbal.
Millions are functionally illiterate, completely put off or puzzled by the printed page.
Many college graduates have never read a book. A second reason is that language teachers today are not very well prepared, I think, to teach. So-called colleges of education are, in my view, abominations that spew out teachers who are certified to know how to teach but sadly know nothing to teach. An high school English teacher is likely not to know a gerund from a ground hog, as this sort of information is now adjudged to be irrelevant. Colleges of education are largely diploma mills that ought to be padlocked.