"Can't risk a background nobody looking better than someone who is paid to get looked at.
Remember the girl handing out water who got a modeling gig?
You think there weren't any angry phone calls about that?"
The runway industry is run by non-lords.
0. They have shit taste.
1. They know they have shit taste.
2. They can't fix the shit taste; lords are born, not made.
It's easy to avoid the poors looking better than your "model" if you pick genuinely pretty people and clothe them with competent designs. It's the real textiles advantage. In real life, I'm constantly coming across women hotter than photographed models.
If you can't, then duh, time to start rigging the scene.