Even worse than it's/its and who's, which in my opinion can at least be understandable mistakes, are things like when someone uses "they're" in place of "there"

Even worse than it's/its and who's, which in my opinion can at least be understandable mistakes, are things like when someone uses "they're" in place of "there" or "their". I could understand mixing up the latter two, but it's like, what do you think the apostrophe means, exactly?? Obviously the answer is that they don't think about it at all, but it is indeed a bit jarring.