Because it does not make economic sense. Also because that is comically inward looking and has a whiff of racism about it on the "shared culture" side..
I'm not sure where you took your sociology class but you ought to know that culture != race. Next time, you might try to respond directly to the person's statements instead of attempting to discredit them through unwarranted accusations of racism.
the distinction I think you're trying to make isn't necessarily racism, but a bias toward ignorance-promoting tendencies to remain ignorant which can have the same result: insulation of thoughts, ideas, decisionmaking from outside views
i don't think it's wrong to say that you could probably find some improvement from an outside perspective and that you may be missing something if you aren't, but I don't think it's a simple enough problem that you can reduce aversion towards change to any single motivation without trying to understand their reasoning