It is the fact that LLM's can't and don't try to write valid programs. They try to write something which reads like a reply to your question, using their corpus

It is the fact that LLM's can't and don't try to write valid programs. They try to write something which reads like a reply to your question, using their corpus of articles, exchanges etc. That's not remotely the same thing, and it's not at all about "accuracy" or "tokens".