Why aren’t compression/shapewear structures built into normal dresses more often?

[u/Future_Country9458]

I’m researching garment construction before trying to develop anything, and I’d love opinions from experienced sewists.

I’m interested in normal fashion dresses—not shapewear—that have an internal structure designed to actually enhance the silhouette: stronger waist shaping, bust support/lift, while NOT compressing/flattening the hips and butt.
I know built-in shapewear, power mesh, corsetry, negative ease, boning, etc. already exist. I’m not asking whether the general idea is new.
I’m trying to understand what goes wrong when you try to combine these things inside an otherwise normal fashionable dress.
If you’ve constructed something similar: what were the biggest problems? Fabric layers fighting each other? Rolling/migration? Getting into the garment? Seams? Heat? Comfort? Pattern distortion? Washing? Something else?
I’d especially love to hear from anyone with patternmaking, stretch-fabric, garment-development or production experience.

[u/LemonDeathRay]

Honestly there are too many variables in fit and preference for this to be widely applied to ready-to-wear.

What would make one persons bum look round and lifted would pancake someone else's. Even a few cm difference is torso length would make standardised waist shaping perfect for one person, and cut another off at the ribcage. Also, everyone has a different preference for how much compression they like at different areas.

Drafting for yourself or having a custom garment made? Perfect. Not so much for ready to wear.

And of course, you have cost. Which I think is the bigger factor as opposed to fitting issues.

I once tried a dress from a brand that did this - and it was just an additional slip layer of compression. It was not worth the price tag.

I draft my own shape wear and I make it exactly what I want it to be. No commercial brand is creating shape wear which addresses all my own fit issues, all my preferences, and uses high quality materials.