I have to say this selection bias exist on the other end as well, perhaps not as blatant as mainland, where the girl gotten her eye shot or the triad beating people wasn't shown at all.
There is selection bias on both sides.
A small nitpick, the news about the girl gotten her eye shot is not hidden from Chinese news, but was presented as being shot by a slingshot of a marble by the protestors (in Chinese [1], Google translate [2]). According to reporters who were at the scene, the girl was definitely shot by the police, because only the police could fire the bean bag round which was stuck in the goggles of the girl and caused such injuries. Put differently, CCP is spreading fake news via state media instead of hiding it from the public view.
Similar story for the triad beating people: it was presented as the triad was trying to protect their homes from the protestors (in Chinese [3], Google translation failed). The news was not hidden from public view.
[1]: https://news.163.com/19/0819/17/EMV7LC0V0001899O.html
[2]: https://translate.google.com/translate?hl=en&sl=zh-CN&u=http...