Keh? Care to elaborate? I'm not being cute, but I honestly have no idea what you mean. How do Bacigalupi or McDonald depict non-Western cultures evolving backwards to pre-1900s culture (if that's what you are in fact saying)? How can something evolve backwards (isn't that an oxymoron)? I can't see what you mean and I can't see this in the books I've read.
Sure. In
River of Gods, many social elements that were already fading in 2005 are back with a vengeance, almost as if they had never left. The importance of caste, for instance. Hindu-on-Muslim pogroms. The Indian admiration for all things British. In this ultra-high-tech future, India has gone back toward being what it was like when the British ruled it. Even the "modern" elements are more 2005 than 2047 - for instance, call centers staffed with chai-wallahs. Even at its most "modern,"
River of Gods often feels like
Slumdog Millionaire.
In
The Windup Girl, this "cultural retrogression" is both A) less pronounced, and B) more justifiable, since technology itself has regressed. But some elements are still there. The characters constantly make references to Thai history, invoking historical metaphors to explain nearly everything. I have a bunch of Thai friends, and they don't even
know that history, for the most part. They kind of laughed when I showed them the parts of the book that I'm talking about.
In
When Gravity Fails, Arab and Muslim history is occasionally referenced, but it's in the background, not constantly trotted out. The main character and others make fun of Islam and of traditional Arab culture, even as it continues to exert a background influence on their society. The Arab characters are aware of foreign icons like James Bond (though ignorant of others). The progress of technology has forced the integration of new cultural elements (transsexuals, for instance) into the mainstream.
All in all,
River of Gods feels like it was written by a guy drawing mostly on internet research and British Imperial cultural memory for his conception of India;
The Windup Girl feels like it was written buy a guy who lived in Thailand for a while and then read some history on his own; and
When Gravity Fails feels like it was written by an Arab living in Europe whose parents moved from the Middle East.
The thing is, the first two are probably accurate, while the third is not the case at all; George Alec Effinger was a white dude from New Orleans. Which makes his achievement all the more impressive.
Also, Effinger has more literary skills, and is better at character creation. Those don't hurt either.