> (even native speakers make mistakes)

> colloquial diverges from the proper grammar.

Since we are here on HN I'll allow myself to jump on your, to the topic of this thread totally unrelated, remarks. A native speaker can't really make mistakes, because what a native speaker speaks, defines the language. The grammars have to follow the speakers, not vice versa. The widespread world view that there is a proper language and beside it a inferior colloquial language needs to die.