I keep hearing this claim, and yet I keep seeing LLM output which is trivially distinguished from human writing.
That's because they're trained that way. If you trained a modern frontier LLM with the explicit goal of passing the Turing test, it would have no difficulty doing so.
Turn on showdead and look at the killed comments on this thread. (Every thread remotely related to LLMs seems to attract this behaviour.) If it's so easy to get it right, how is there such a high fraction of failures?
That's because they're trained that way. If you trained a modern frontier LLM with the explicit goal of passing the Turing test, it would have no difficulty doing so.