I bet you will hear something like they are homogeneous.
That won't work, for the very simple reason that it doesn't take into account fundamental aspects of human nature---that even if you have just "the same type" of people, they will find reasons to for "destructive differentiation". "Clans" within a "tribe", "sub-clans" within a "clan", etc. Even in the USA not all whites are "the same": people will note the differences between, say, "proper whites" and "white trash".
As far as I can tell, "homogeneity", regardless of the "level, helps only when looking outwards---Us vs. Them. When looking inwards, i.e. all "Us", it is quite another matter.
Anyways ... I have lived in some of the countries I listed and still regularly spend time there. So I'm keen to see any "homogeneous" argument.