Evaluating LLMs is incredibly difficult. They are categorically different from any other system we have intuition about.

That said, I read the question I am replying to as a rhetorical one. If it was meant as a genuine question, curious about the question of meta knowledge, then I misread. Certainly the question is extremely interesting, for both LLMs and humans! But it's also obviously a very difficult one, as we don't even have a clear theory on how "knowing" works in the base case.