What is the biggest difference between monoracial nations and immigrant nations?

That's the question Rhie Won-bok asks in Chapter 7: Credit is Life, How Americans Live. Seems unconnected until you understand Rhie's theory that American dependence on credit is based on racial factionalism, the underlying weakness of immigrant nations. A note to the reader: I have translated the word 민족국가 variously as 'monoracial nation' and 'nation state'. Be aware that this term refers to a country in which everybody more or less belongs to the same ethnic group. Also interesting to see homogeneity used as a positive term, something which took some getting used to for my American mind.

p190)
What is the biggest difference between monoracial nations like Korea and Japan and immigrant nations like the U.S., Canada, and Australia? In a nation state, the citizens have a common 'homogeneity'. Even without explaining, we can say that compared to the "citizens' heart" that everybody knows, the immigrant nation's citizens with their various and complicated origins fall far from this homogeneity. It's not only morals and ethics but in values as well, nation state citizens have these in common while immigrant nations' citizens are different from each other. Even if we say nation state citizens have various personalities, they have a strong commonality between them, while the immigrant nation's makeup of various races and peoples have a much higher likelihood of clashes and friction than nation states.

p191)
Even if they are very careful they can always suffer these clashes. So in order to minimize unnecessary friction and to keep from damaging others and being damaged by others, the best method is to erect a 'protective wall' between oneself and one's surroundings. This protective wal is a way to concea oneself and not to show one's true feelings and true self to anyone. Even though in a society where everyone lives behind a protective wall arguments are kept to a minimumm we can call this a society where people use fundamental rules and law to solve their problemsinstead of using faith in each other and heart (정). This is why even though the image Americans show people seems warm, the moment they turn around they are completely different.