"Banner blindness [...] describes people’s tendency to ignore page elements that they perceive (correctly or incorrectly) to be ads." https://www.nngroup.com/articles/banner-blindness-old-and-ne...

So people can focus their attention to parts of content, specifically parts they find irrelevant or adversarial (like ads). LLMs on the other hand pay attention to everything or if they focus on something, it is hard to steer them away from irrelevant or adversarial parts.