This is amazing! The rest of this thread completely buried the lead. Delightful.
One of the reasons children learn new languages quite rapidly is because they get corrected the whole time.
Not correcting people hinders actually their progress in language learning… Even if it might seem impolite it's the one thing that helps a lot, if not even most, in mastering a foreign language!
So thanks for being a "grammar nazi". We need people like you.
(No, that doesn't apply to the causal typo. But I guess most people can differentiate such a thing form true grammar and spelling mistakes; especially if that are "typical" mistakes).