I like never reading “should of”, as well. Every browser and phone’s autocorrect aggressively suggests a correction to “have.” Sometimes you don’t notice an apostrophe appearing in the middle of a word, so I can forgive “it’s,” but there’s little excuse for fighting with autocorrect to write “should of.”
Fewer mobile users maybe? For whatever reason, autocorrect/autocomplete suggestions on iOS always tries to add inappropriate apostrophes to plural words. Without fail, every single time. I sometimes reflexively tap the autocomplete suggestion to finish longer words and it’s really aggravating.
Why do you care? Why does anyone care? You understand what the person means, that's the most important thing when communicating. Grammar on the internet is so unimportant, even people who know the difference might not care enough to coerce autocorrect into choosing the right one.
If you can't type a text message with proper grammar then you can't type anything else either. It doesn't take almost any more effort to do it right. If your writing is full of mistakes you sound a bit stupid. You don't need to be perfect but you should atleast try.
Also the joke was that I incorrectly typed "its" there