I see it all the time in basically every form of text communication. What makes you think you are not seeing it?
I think those who are very opposed to AI often don't know much about the real limitations since they don't use it, and their complaints are often a year or more out of date.
I think the ideal demographic for spotting these are people who use the frontier LLMs a lot and they also have worked with text in detail, such as copywriters, people who have learned foreign languages and grammar etc., have edited articles for language and generally have a more "wordsmith" look at language and are sensitive to flow and rhythm of language on a more technical level.