Because people aren't used to the idea that computers will make things up. I don't see why anyone is surprised by what the lawyer did here and for sure there is

Because people aren't used to the idea that computers will make things up. I don't see why anyone is surprised by what the lawyer did here and for sure there is a lot more of this going on than is getting into the public. People spend their whole lives thinking of machines as logical and correct, but lacking in creativity. Suddenly generative AI comes along and totally upends this. If you're an HN reader and see in depth discussions of LLMs every day then of course it's obvious that these things can make up citations, but if you primary experience of the tech industry is search engines that have never made up fake results ever, then why would you even imagine it's possible?