I spent my teaching career in large part trying to train Canadian college students to spell their own language. (Those were 40 years I'll never get back.)
My own high school had done a pretty good job of teaching us how to spell in the 1950s, so I was surprised, less than a decade later, to find myself teaching students innocent of grammar as well as spelling.
It took a while to realize that I'd been "streamed" into relatively intensive courses -- my English 3A wasn't as good as the super-brainy English 3XL, but it too was designed to prepare me for college. And it was far ahead of English 3, where working-class and minority students usually ended up.
The North American surge into post-secondary, which had begun just as I was starting college, had by 1967 carried a lot of unprepared kids into universities and community colleges, where we instructors were shocked and appalled by their subliteracy. Little did we know that teachers have for centuries expressed the same despair about their students, including us.