As a teacher who has to grade written assignments, I find all these too (to, two) familiar.
Often my students get your and you're mixed up.
I get the impression that then and than are interchangeable in their minds.
Too many of them do not know what to do with an apostrophe.
More than half of these soon-to-be-college-graduates don't understand the difference between plural and possessive.
Quotations with punctuation marks are an opportunity for creative thinking.
Capital letters appear inside sentences in the strangest places.
Run-on sentences are epidemic, as are incomplete ones.
And then there's this strange thing called a paragraph, which seems unfamiliar to some.
Introductions and conclusions are way too complicated for them to think about.
I don't let my college students get away with these things even though I am not an English teacher, but clearly other faculty do.
When I was young I never thought I'd be the adult complaining about the kids, but here I am doing just that.
Maybe it's not worth the fight, and the grammar rules should change to match what the general public actually does.