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Watching Friedman interview people, though, it's clear where it comes from - Friedman himself. The interviews were all in English with largely (if not totally) non-native English speakers. When someone would answer a question, Friedman would rephrase it using an American idiom, say it to them, and wait for them to repeat it back to him. Sometimes it would work, sometimes it wouldn't, but it strikes me as an apt enough explanation for why people in Friedman's columns seem to be using his words. It's because they are.
I'm not sure how much better this is than theory b - the "just makes shit up" theory.