But why are oil and water treated differently? After all, serious interruptions of food (virtual water) would also stop highly developed economies in their trac

But why are oil and water treated differently? After all, serious interruptions of food (virtual water) would also stop highly developed economies in their tracks. It seems a crucial test for his thesis, but he doesn't clearly address it. Is it just that trade in oil is more easily controlled because (1) it has few sources, and (2) the economy of a country that sells food is itself hugely dependent on those sales? (that is, symbiosis is the best foreign policy?)