Many cities on the Chinese mainland are nearly as wealthy as Hong Kong but none of them are remotely as "international".
And asking "why are [Hong Kongers] not fighting for better rule of law in all of China? Where is the solidarity?" either betrays a serious lack of understanding of how the Chinese political system works or is a question asked in bad faith.
We have no idea of knowing, but from what I've heard, they are simply not aware. Almost anything with the phrase "Hong Kong" was censored inside mainland China today.
It's not too hard to find something on Weibo, e.g. this post in support of the police [1] where the highest-upvoted comment at 281 votes condemns the police violence [2].
Huh? That not everyone agrees doesn't mean nobody believed her. The highest-voted reply complains about censorship. The second-highest talks about the police acting in self-defense. The third-highest fantasizes about shooting ... someone (I initially interpreted it to mean the police, but maybe they actually want to shoot the protesters?)
Chinese government is paying Chinese people 500 HKD (Hong Kong dollars) to cross the border and counter protest so that they can report there are 800k counter protestors.
And asking "why are [Hong Kongers] not fighting for better rule of law in all of China? Where is the solidarity?" either betrays a serious lack of understanding of how the Chinese political system works or is a question asked in bad faith.