One answer, as another person pointed out, is that LLM mistakes are just different. They are less explicable, less predictable, and therefore harder to spot. I can easily anticipate how an inexperienced engineer is going to mess up their first pull request for my project. I have no idea what an LLM might do. Worse, I know it might ace the first fifty pull requests and then make an absolutely mind-boggling mistake in the 51st one.

But another answer is that human autonomy is coupled to responsibility. For most line employees, if they mess up badly enough, it's first and foremost their problem. They're getting a bad performance review, getting fired, end up in court or even in prison. Because you bear responsibility for your actions, your boss doesn't have to watch what you're up to 24x7. Their career is typically not on the line unless they're deeply complicit in your misbehavior.

LLMs have no meaningful responsibility, so whoever is operating them is ultimately on the hook for what they do. It's a different dynamic. It's probably why most software engineers are not gonna get replaced by robots - your director or VP doesn't want to be liable for an agent that goes haywire - but it's also why the "oh, I have an army of 50 YOLO agents do the work while I'm browsing Reddit" is probably not a wise strategy for line employees.