I found that many people don't have a radar for this. They may know about delve, emdashes, tapestry, multifaceted or "not just X but y" and if these are not there they don't see it.
They probably don't care enough to notice the tells. I think that it's generally those ambivalent, skeptical or opposed to AI who notice, while those who wholeheartedly support AI see no reason to differentiate between it and humans and so do not even try to.
I don't think it's that simple. I'm not blanket opposed to it. I'm more along the lines of the author of the article. Use it for what it's good at, sift through unstructured info, convert information from one format to another, implement things that are planned out well with iterations and feedback, etc, and generally mapping out the capabilities.
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often don't know much about the real limitations since they don't use it, and their complaints are often a year or more out of date.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.