"Anywhere in the world that social psychologists see women or minorities underrepresented by a factor of two or three, our minds jump to discrimination as the explanation,” said Dr. Haidt, who called himself a longtime liberal turned centrist. “But when we find out that conservatives are underrepresented among us by a factor of more than 100, suddenly everyone finds it quite easy to generate alternate explanations."You know what doesn't happen? A black woman avoids sensitive topics in a job interview, leading the hiring committee to incorrectly assume that she's a white man. And you know what else doesn't happen? A demographically average population spends a great deal of time discussing race and gender issues, with the result that most of the women decide to become men and most of the black people decide to become white.
Mapping the way race and gender work in our lives onto the way that politics works will result in comedy. The reason everyone finds it easy to generate alternative explanations of the prevalence of liberals in academia is that the alternative explanations look pretty good, and the explanations involving anything that matches racial or gender discrimination just look pretty bad.
Those who live close to the marketplace of ideas will find it easy to acquire new ones. So you'd expect that academics everywhere would abandon parochial values and adopt a more cosmopolitan perspective. My philosophy department in Singapore provides a pretty nice cross-cultural example. The Singaporeans, other Asians, Americans, Europeans, and Australians have generally egalitarian views on civil rights questions, with little tolerance for nationalism. (We disagree more on economic stuff.) This is exactly what you'd expect from a global community of scholars who have to defend their views against each other's criticisms -- the elimination of local prejudices that don't stand up to rational scrutiny.
There's plenty of other stuff going on too, of course -- if professors and executives got each other's paychecks, the professors would suddenly get a lot more interested in lower taxes on the rich, while the executives might drift to views more favorable to middle-class interests. And when you've got a core group of non-rich people who have given up their local prejudices, they'll attract more people like them. But the overall point is just that when a global community of scholars agrees on something, "they've figured something out" is usually a better conclusion than "they're all prejudiced."