They look similar. In my experience, they do not read similar at all. You have to pay attention and actually try to appreciate what you're reading. Then, if you try and fail, it might not be your fault.
What effort was put into their prompt to make them read similarly? There could very well be a selection bias, where you're only "seeing" AI when it's obvious/default prompt.
They do not read similiar to readers, an appellation not necessarily applicable to large swaths of the U.S. right now. Evidence of English composing skills is being assumed as AI because few younger than my middle-aged self can conceive of writing composition at the skill level demonstrated by AI being a human skill.
(This isn’t necessarily true for first world countries, which is why I describe it for the non-U.S. folks in particular.)