Misspelling is a sign of disregard for rules. People who misspell are the same people who will likely commit traffic violations or refuse to assimilate in Canada, if they came from elsewhere. Languages evolve over time but not because of misspelling. Misspelling does not lead to evolution but to linguistic corruption. It must be avoided at all costs. Email, text messaging and other forms of communication are not an excuse to misspell. I have no problems with people who interrupt others to correct their grammatical/spelling errors. The problem is not with them. If you tolerate misspelling, the problem is with you!
I grew up watching Sesame Street and also a good number of books. When you see the printed word you begin to recognize them instantly by the way they are spelled and when you go to write, you spell them just the way you had seen them. I don't know what's happening in classrooms these days as I don't have any kids, but you can be sure spelling is no longer a priority.