using an apostrophe to indicate possession is the common case.
For nouns, but not pronouns. Compare his, her, my, their, ...
As for comics, perhas I should not admit to liking this one.
The objection that it's not a procedural knowledge gap is probably valid. But I was not just ranting; I asked a number of questions in the answers to which I am genuinely interested. And whether I feel superior to people who use apostrophes incorrectly does not strike me as relevant--although I try not to, and understanding why they do it might help.
Although I note that the OP does not mention the 'procedural' restriction.
There's been a recent heavily upvoted and profusely commented post about things people want to learn. It's close to having so many comments in a single day that it should probably have a part 2.
However, the subject seems to inspire thoughts about what *other* people ought to know, and while that's got a good bit of overlap, it's emotionally rather different.
So, what do you think other people ought to know? Any theories about why they haven't learned it already? Any experience with getting someone else to learn something when it started out as your project rather than theirs, especially if the other person was an adult?