We could consider lifetime costs. A human requires other humans to build, takes 16+ years to grow to reasonable capacity, can't work 24/7 or even a consistent 40 hours a week...

That's why I fully expect supermarkets to have drastically reduced labor costs in a few years, as shelved goods will be restocked by micro-forklift robots, checkouts will be automated and the human staff is reduced to two or three supervisory and customer-relations positions.