He said in the video it's cheaper through the economics of reuse, not through it being cheap itself
Maybe easier to clean, or wash out vomit, or even warn of forgotten items.
If people are willing to pay extra for comfort and style already, why would they stop?
I feel like so much of this discourse is dominated by people who hate cars. Most people like their cars! That's why they bought them.
There is logic in this design being cheaper to manufacture but I would think that it would be a long while before you "broke even", so to speak, compared to using a design that you already know exactly how to make.