Guilty as charged. Before my bank had an ATM, I organized my time differently, but I survived.
As for dignity, it's not versus "a job that can be more efficiently done by automation", it's versus "being unable to find a job."
Forget the sandwich clerk; schoolteachers are found somewhere along this trajectory.
I would answer almost all of the questions in your first paragraph "yes." I agree with all of your ideas in paragraph 2, so I think there is much we agree on, despite that.
I think it is in society's interest to arrange for there to be a number of job-vacancies of the Panera-kid-type available, even if that is not the sandwich-delivery mechanism of minimum cost. In principle, we could do better, but I am skeptical that it will happen.