I recently read Pricing Beauty: The Making of a Fashion Model by model/sociologist Ashley Mears. It's an interesting, if rather dryly-written, book about the economics and culture of fashion modeling. (And I was surprised reading it to realize that I know the male model "Michel"--he comes off as way more of a freak in that book than he is in real life, I think because English is not his first language. If you write nonfiction, please note how simply changing someone's name is not nearly enough to protect their identity.)
Anyway, Mears points out that there are two major schools of modeling: Commercial modeling (catalogs, advertisements) and editorial modeling (fashion shows, magazine shoots).
Commercial modeling is seen within the industry as, you know, commercial. Hot babes do well. But it's also regarded as Not Art--the idea is to appeal to Middle America, not challenge it. You or I probably have just as good an eye for a commercial model as anyone in the industry.
Editorial modeling is seen more as an art form. Those seriously bony girls with light-green, shiny skin and no eyebrows? They are editorial models. They are considered high fashion and on the cutting edge. While commercial models are pretty and sexy, editorial models are edgy, avant-garde, belle laide, and many other French terms for funny-looking. While commercial models are supposed to appeal to Middle America, editorial models are supposed to prove that whoever is trumpeting them is a true artist, with a unique and fabulous eye.
Which, as Mears points out, means that editorial models are suppose to appeal to other people in the industry.
Given how cutting-edge editorial models are supposed to be, how they are supposed to challenge conventional notions of beauty, which group do you think is more diverse?
. . . ?
Commercial models. Yuppers! People actually do market testing with commercial models, and it turns out that Middle America is actually a pretty diverse place! If you're pretty and sexy, no one cares much what your racial or ethnic background is!
Editorial models, in contrast, tend to be white, white, white. And really anorexic. (Apparently there are no really good non-white models in existence. It's kind of funny to watch the RAGE boil out of Mears' academic prose in response to that one.)
It turns out that if you have this small little gaggle of people who all socialize together and who are all constantly judging each other's taste, that taste becomes really homogenized--even if these are people who pride themselves on seeing the world differently!
I think that's a big part of why you get homogeny in movies and commercial books, too--it's not just the financial expectations that make everyone in the industry seek to produce clones of the latest hit. It's that tendency to move as a herd--everyone's in the same city, they have worked or will work together, and they do tend to socialize together. Consciously or not, they don't want to piss each other off, and that makes even their "edgy" decisions very, very safe--within their world, anyway.