> nor do they respond "Sorry, you're right, 1+1=3, my mistake" without some discernible reason.
Look up the Asch conformity experiment [1]. Quite a few people will actually give in to "1+1=3" if all the other people in the room say so.
It's not exactly the same as LLM hallucinations, but humans aren't completely immune to this phenomenon.
[1] https://en.wikipedia.org/wiki/Asch_conformity_experiments#Me...