Why are some brands honest about some fibers but not all?

Hi! so i had this question for a long time and it really bothered me, because i see this not just in huge brands like HouseofCB but even in brands that differentiate themselves from fast fashion.

I've noticed this trend where when cotton, silk, linen, etc is involved they boast about it as a selling point, but whenever it's polyester, nylon, or a blend, they be as vague as possible about the fibers, so instead of 100% cotton or 98% cotton 2% elastane it's like "made of the most high quality french chiffon" or like "made of premium satin" and one i saw was "Made from a soft ITY jersey" and i was like what on earth is ITY fabric? googled it and “ITY jersey stands for Interlock Twist Yarn jersey. It is a popular, stretchy knit fabric typically made from a blend of polyester and spandex.” You couldn’t have said 95% polyester 5% spandex??? it's very frustrating especially with slower fashion or sustainable brands because the whole point is transparency? why do i have to go through hoops to find out what i'm spending $200 on?

has anyone else noticed this trend? and if so how do you feel about it? what do you do when trying to shop from brands that do so?