For Brooks, culture is something that's out there, and which arises, fully formed, from some kind of pervasive but nebulous ether. Politics (and economics) is fully downstream of that, and is completely parasitic on this ex nihilo culture. This is pretty much a paradigm case of your brain on idealism : it's the ideas--in the form of culture--that shape our political economy on this view, but not the other way around; politics and power never "act back" on culture, but are forever subservient to ideology. This gets the arrow of causal influence almost perfectly backward. As you say, the predominant beliefs of most Americans are shaped by decades of material conditions--propaganda, immiseration, austerity, and political capture by the richest of the rich. Even if we grant that he's right in describing the views of most Americans (which I think is actually pretty suspect too), Brooks never thinks to interrogate why and how people come to have the views that he attributes to them; we just think what we think, and then shape our world in response to that bundle of ideas that God has placed into our minds. Politicians, on this view, are merely weathervanes whose job it is to act based on the ideological winds, forever hostage to their vagaries and totally unable to shift their direction.