they should make clothes that are designed by people who are familiar with human anatomy & physiology
Yeah it's not that at all. Tailors exist. They share in your disdain.
It's all about the money. Patterns will be cut from cloth with the least amount of scrap left, with no regard for the orientation of warp and weft. On top of that, fabrics aren't preshrunk before they are assembled into garments so now you're going to get shrinking that IS affected by orientation of warp and weft so you're gonna buy a 3 pack of white tshirts and after one wash all three of them will fit and twist differently
Capitalism sucks so bad