My bugbear is the far more basic "Mom's" to denote the plural. I see it frequently, even when people are otherwise reasonably literate. What the fuck is going through the head of someone who just whacks an apostrophe in there?
In fairness, autocorrect does it sometimes. I'll gets corrected to I'll - see what happened there. Normally, I'll check before posting, because I don't want people thinking I'm an illiterate idiot who doesn't know how to use an apostrophe.
But yes, there are an awful lot of people who really don't know.