Well one thing I can say is that as far as really good resources/ multiple shot nude photos of the same person tend to be much more accessable for caucasians. I find one ethnic fully nude set of body and face shots for every ethnic one.  The lack of these photos might be one reason for the reduced number of 3D model textures and merchant resources that are ethnic.

"People who attempt define what art is or is not, are not artists"---Luminescence