I believe that should be "knows". [But the Sarah bashers knew what you meant and didn't feel a need to pretend that you don't know the difference between subject-verb agreement and possessive based on a minor slip.]
Of course. It's a curious mistake.
I know that I can readily type "their" instead of "there". Because my vision isn't what it should be, I sometimes can't see clearly what I have just typed, though I always proofread my posts.
I think it might be that I was mentally anticipating the apostrophe in "government's" and somehow threw one in early. I'm a self-taught typist and apostrophes take a disproportionate amount of time and effort.
The mistaken uses of "their" and "there" I think are due to the brain hearing the sound and failing to choose properly while typing. I DO know the difference and I think I have improved my accuracy rate on this through increased attention. I'll have to pay more attention to apostrophes.