What????? I work in a school. You don't think we teach this stuff, do you? We work hard to combat improper English, but how do we possibly have control over the way students speak at home?
Of course I don't think you teach this stuff, but the US Educational system is in shambles. Too many students are put in special education for behavioral problems, kids are being promoted to grades without the ability to read and write properly. Trust me, I have taught at the university level and you would be surprised at undergraduates coming in that can't read and write properly.
I just wanted to add, that speaking and knowing proper standard English is quite differently than spelling and grammar errors. I minored in journalism in college and worked as an editor and even editors sometimes need editors, which is why they have copy editors. Of course, gross mistakes is a sign of a serious deficiency, but I have seen some brilliant minds such professors, teachers on all levels, that make some horrible spelling and grammar issues, at times. Why do you think they invented spelll check?
I do believe and agree that languages are fluid and change over time.