I believe the point that is being made is that the US was designed from the outset with the idea that diverse factions compete against factions, and that was the only way such a large and varied democracy could work. See Federalist 10.
Citizens of the US have wildly varied views about what it means to be a good American, and we often have greater cohesion to groups such as race or state, etc. Just about the only thing we do agree upon is when there is an existential threat to the country, hence military growth over time.
Cuba or Norway have much less divided societies to govern, and Cuba's leadership is so small that it can focus on specific issues in a way US politics cannot.
