The difference is you can evaluate a small bit of the output of a human or a team of humans and expect all their other code to be roughly in the same ballpark of quality.

An LLM can’t be trusted to produce code and make higher level project structure choices of the same quality at all times, because it can’t be trusted at all - trust is for deterministic systems. But still it begs us to trust it. Every prompt that yields good results sets us up to expect good results, so we get lazy - and then the next prompt it spews out garbage.