This seems like a perception thing. Like the person moving rocks might be extremely grateful just to have a job. The mentally disabled, ex-cons, and other people who have been overlooked for work for many years all likely experience a sense of dignity in being paid to work. Perhaps they even delude themselves into thinking moving rocks is somehow useful or necessary.

I always found it weird that outsiders need to dictate what dignity is, since it is an internal state/feeling about own actions.

I’m not against automating high toil (the definition from the Google SRE book) jobs. But people will find dignity in their hobbies if they can’t find it at work. If they can’t find dignity there, they have been failed by society.