I think your confusion here stems from the fact that you're talking about automation vs. non-automation, e.g. whether a person or a robot does a specific job.

I think your confusion here stems from the fact that you're talking about automation vs. non-automation, e.g. whether a person or a robot does a specific job. I'm talking about the jobs that actually get done. Not every task that a human (or robot) performs as labour is essential. For the most part, the human ends up doing the thing that pays them the most. It's not necessarily the case that the thing that pays them the most is best for society. Imagine that, for example, building video games and being a nurse are both non-automatable tasks and both have no upper bound. Let's assume building video games is a higher paying job. It's not necessarily the case that a person who can do both should do that. It may be in their own interest and the interest of their employer but not wider society.