China is a very authoritarian state, and control at this level is not unprecedented.
All that has changed is the West's willingness to close its eyes and deal enthusiastically with China, whose economy has transformed in the last 30 years or so. Human rights are rarely mentioned when dealing with China
That's why the protests in Hong Kong have come about. They do not want any aspect of the SAR eroded by transfer of any of their rights or institutions to mainland China. This was meant to be protected until 2047, with UK having a role in their maintenance (both sides ageeeing in the Joint Declaration) but China is now saying that UK should keep out of HK SAR affairs (despite treaty obligation agreeing to that) and has been saying the JD is dead for the last 5 years or so.
And that's another aspect. China does not permit any interference in its internal affairs, and a successful way to influence has yet to be found.