[berthe]

> Probably a combination of all three. The US and China have the benefit of a comparatively gargantuan native population that all speak the same language

As odd as it sounds, my understanding is that China's Han population doesn't all speak the same language, but they (for the most part) read/write the same language. They call the variations in spoken language "dialects," but many of them are mutually unintelligible. I think the situation is the similar to a hypothetical one where the Romance countries (e.g. France, Spain, Italy, etc.) speak their respective modern languages, but continue to write exclusively in Latin.

Just a small unimportant quibble that doesn't negate your larger point.

[tomp]

Still, the difference is size. In China, 20 million people speaking the same language is a city. In Europe, it's a country.