This seems correct. American culture is definitely, in many ways, more extraverted than Russian culture (the only other culture I have significant experience with), despite (somewhat paradoxically) the greater emphasis on collectivity in Russian culture, and a somewhat lesser attention paid to many classes of social faux pas than American culture. "Familiarity" is a greater social sin in Russian culture than it is in American culture.

As a corollary to this, people raised in the Russian culture generally view American social interaction as "fake".

I remember discussing today how 'constant improvement' -- a classic introvert value -- is an everyday concept in Japan. So, yes. I do think that there's a general self-selection effect regardless of culture, where introverts don't get as much of a say in social norms precisely because they are usually less involved in socializing, but that's just speculative currently.