You mean "some humans know and could say so". And this reflection process is not captured in the data we fed to LLM-s (like let's say a lesson in which teacher

You mean "some humans know and could say so". And this reflection process is not captured in the data we fed to LLM-s (like let's say a lesson in which teacher asks "do you know X?", and students first answer "I don't know", etc.) Also, LLM-s could report more statistical measures for each answer and external tools could interpret them.