These people are part of the reason a lot of people outside the US think that Americans are stupid.

Also, I've marked university level assignments, I only deduct marks if the spelling errors are rampant. One mistake doesn't necessarily indicate a failure to spell as much as it might indicate a lack of careful proofreading. It's usually when I have to start having to decipher someone's spelling in order to understand their point that they start losing marks. But then I'm marking science courses.