If both guys are smart, the hard working guy will find a better way to do the tasks and use the extra time to do other work.

The hard working guy will likely spend more time validating that the automation works correctly while the lazy guy won't. Checking every detail, tracking down the source of any issues and fixing them so they won't occur again is a lot of work. The lazy guy doesn't do that.

What the lazy guy does could be done by an LLM, what the hard working guy does can't be.