>>3432286>Why does an XS cost the same as a XXL when there is twice as much material or more used in one of them?1. The premise of your question is flawed, because usually plus sized clothing *is* more expensive.
2. It's not more expensive for most of the incremental sizes (e.g., S to L usually cost the same) because the incremental material costs are usually tiny compared to the labor cost of manufacture. Ie., clothing manufacturers save more money by simplifying their price structure than they would get by pricing every size individually. But even so, they usually have regular sizes at one price and plus-sized sizes at another.
Source: I am extremely fat and buy my own clothes.