I agree for the most part, but keep in mind that "old" nations like Switzerland and Germany have a distinct advantage here. Family relationships trace back literally centuries and there is a strong sense of national tradition, which implies some level of ontological agreement and makes democracy possible to some extent. This shortcut does not apply to implementing a functioning democracy in, say, some "nation" of diverse ethnic groups arbitrarily carved out by British imperialists in the 19th or 20th century (see Africa and West Asia).
> "common sense will sort it out over decades"
More like centuries. USA has been a nation for 250 years yet we are teasing a second crisis of separatism. Immigration definitely plays a big role here. Political consensus takes generations to settle.
Families yes, but I nees to push back against the idea of national tradition and ethnic homogeneity mattering here.
The nation thing is very much not the case for Germany and Switzerland at least. France more, and for homogeneous population maybe the nordics but the myth of the ethnically homogeneous long nation state is something that I mainly hear from conservative/right wingers who want to claim diversity doesn't work (not implying you are, just in general). The comparison with a colonial overlord carving out a centralised nation is also not too relevant, except that I agree that was bad and trying to impose European civic systems without also building the infrastructure and economy to support them doesn't work?
But Germany the nation was born in the late 19th century (Bismarck, Prussia taking over etc) and modern Germany has a complicated relationship to the old nation and nationalism in general. In Switzerland, they are literally 4 ethnic groups with regional fracfionalism tied together by will and democratic traditions, any ethnic stuff doesn't really apply there.
> "common sense will sort it out over decades"
More like centuries. USA has been a nation for 250 years yet we are teasing a second crisis of separatism. Immigration definitely plays a big role here. Political consensus takes generations to settle.