Because they are being very silly.
Hong Kong, Taiwan and Tibet are parts of China and have been for countless centuries, apart from an expired 99 lease on Hong Kong. Resisting the democratically elected government in such a country is stupid, especially when the great majority are happier with today's China than ever before in its long history.
When the lease expired we offered the 3 million in Hong Kong the chance to come to the UK but they didn't take up the offer, happy to stay put. And for all the more mature there that is still the case, the civil rebellion is almost entirely of the young. If they want to live in western style, they can still come here, but they prefer to be cussed. I've got no sympathy for idiots like that.
When Mao Zedong beat Chiang Kai-shek in their civil war, he won and Chiang and followers fled to the offshot island of Taiwan, which as even the Americans say is wholly a part of China. With the USA getting ever more aggressive, China is no longer prepared to put up with any pro American elements on their territory so they are insisting quite rightly on governing the whole of China as one country, and that includes Hong Kong and Taiwan.
The Tibetans are not all unhappy with China resuming closer governance, far from it, since they've benefitted so greatly with new infrastructure which they are increasingly using. And as for human rights, there's been a huge reduction in the practice of taking boys age 7 from their families and forcibly brainwashing them into becoming monks, regardless of their wishes, an evil is ever there was one.
As for the Uyghurs, they werre conquered a very long time ago and have had centuries to get used to being in China. But being Muslims there are elements who recently have wanted to rebel against China to cause a local civil war in the north. They have two sensible options, toe the line and practice their religion peacefully while co-operating with the state in all other respects as they've been doing for most of the last 100+ years. Or emigrate to an Islamic country which China is perfectly happy to allow since they are not a closed state.
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