I agree to disagree, it was misspelled because it was the wrong word.
Two is different from to and too. One letter difference in spelling makes it a new word.
Also, in trashy's case, the dictionary would have helped because it would show the definition of the words and helped him/her/it choose the correct word.
Also, as trashy said, and in agreement with what you said, things like spellcheck and autocomplete make it real easy to type along really fast but pick the wrong word.