If someone is an illiterate devout pentecostal Christian who lives in a village in Angola, the eventual output of the preference formation process applied to them might be very different than if it were applied to the typical LW reader.

Consider the distinction between whether the output of a preference-aggregation algorithm will be very different for the Angolan Christian, and whether it should be very different. Some preference-aggregation algorithms may just be confused into giving diverging results because of inconsequential distinctions, which would be bad news for everyone, even the "enlightened" westerners.

(To be precise, the relevant factual statement is about whether any two same-culture people get preferences visibly closer to each other than any two culturally distant people. It's like with relatively small genetic relevance of skin color, where within-race variation is greater than between-races variation.)