Fashion models exist on diet coke and cigarettes. They often are so thin they don't have a period. That is just the price they pay. Many have eating disorders.
Cameras add weight. That is a fact of life. Clothes look better on skinny models. They hang better and they flow better. Therefore models have to be 10 pounds less than they look in the ads. They are also often immature teenagers when they begin modeling so they don't even have women's bodies yet.
If anything they are as much a victim of the fashion/fantasy world as young girls/women looking at the ads. Oddly most models because of their body types are rather small chested. If girls/women are really trying to emulate them, why do so many women get breast implants so they can look like they're smuggling cantaloupes.
Marketing of all sorts is merely selling fantasy. If you are stupid enough to buy into it, without understanding it, that is your problem.