> robots is that you can also stop production instantly if demand goes down. You have much fewer costs when not at full capacity.
I think you have this exactly backwards.
In a highly automated factory the main cost is capital, i.e. the machines might cost decades worth of payroll. So having them sit idle is extremely expensive, or to say it another way, producing nothing saves you almost no money.
A low-automation factory is the opposite. Big traditional garment factories are basically just sheds with some tables. Almost all the cost is workers, and in many places & times you only hire them when you get a big order.
The automated garment-sewing machines (if we get there) can't do anything else. Factory robots aren't very C-3PO. Whereas the sweatshop workers can be assembling cellphones (or building rice terraces) next week.
It might even be true that robots might not be cheaper than human labor but have other advantages that make them preferable.