China's legislature amended Hong Kong's constitution to add the new national security law precisely because the Hong Kong legislature - even under heavy influence by mainland China - was unable to pass it.
You are correct to point out that force was not used (n/m the divisions of tanks that have been on the border), and Taiwan is different.
You are in disagreement with the BBC on this point:
https://www.bbc.com/news/world-asia-china-52765838
> The Basic Law says Chinese laws can't be applied in Hong Kong unless they are listed in a section called Annex III - there are already a few listed there, mostly uncontroversial and around foreign policy. These laws can be introduced by decree - which means they bypass the city's parliament. Critics say the introduction of the law this way amounts to a breach of the "one country, two systems" principle, which is so important to Hong Kong - but clearly it is technically possible to do this.
Remember, this almost certainly wouldn’t just be a straight-up invasion. I’d assume something more like funding pro-China political parties, expanding business and other ties, and then at some point an incident involving a friendly politician asking for help which never leaves. TSMC is important but just one business and not one many people are going to go to war over when business is going to continue mostly as usual.
https://thediplomat.com/2020/04/trump-quietly-signs-legislat...
He was also the first US president to speak with a Republic-of-China president. https://en.wikipedia.org/wiki/Trump%E2%80%93Tsai_call