More unconscious dualism?

Perhaps I'm missing something, but what is remotely surprising about finding cultural differences in the brain?  If two people think differently, that means their brains work differently, for whatever reason (perhaps because of education, or other experiences, or physical trauma, or disease, or genetics, or drugs, or nutrition; we know lots of things that affect brains).  Examining their brains in enough detail will presumably be able to reveal this difference.  Why isn't this result incredibly obvious and commonplace?