Question: who makes the robots, and are the robots maintained by other robots, and are they cheap and breakdown-proof?
Labor is everywhere in a factory, and even robots require labor from humans.
I’m not sure I understand your question. Tesla isn’t using 600 robots to make the castings - they eliminated the need for 600 robots. So the savings affect everything: Cost of the robots, the factory space, the electricity, and all the human labor to operate everything. The casting machines are the size of a house and cost like $10,000,000 but that is much less than 600 of the other robots.