[1] https://web.archive.org/web/20210216044709/https://www.justi... - linked in [2], though the original is apparently no longer available
[2] https://www.nytimes.com/2022/01/20/science/gang-chen-mit-chi... - 'U.S. Drops Its Case Against M.I.T. Scientist Accused of Hiding China Links'
[3] https://www.nytimes.com/2023/01/16/nyregion/nypd-officer-chi... - 'U.S. Asks to Drop Case Accusing N.Y.P.D. Officer of Spying for China'
So we are politely asking the Chinese Communist Party to stop spying on us, rather than closing down these outposts ourselves. Is this a sustainble/durable option? Our open systems are simply a vulnerability for daring autocracies.
Western countries are hilariously underprepared to deal with adversaries that are both sophisticated and brutal. Adversaries like China, Russia and Iran.
I suspect that the countries involved have legal system which require a degree of evidence which may not be available (or which they may prefer not to reveal in the kind of process that would be required, given the possibility of resolving the problem without doing so) yet before forcibly taking action the way, e.g., the US just has, but there is no strict proof threshold for lodging a diplomatic complaint.
Because neither is particularly relevant here; these are actions in places under simple US jurisdiction, by people under simple US jurisdiction, not by PRC diplomats and/or carried out in facilities that are PRC extraterritorial enclaves.
EDIT: For the arrestees. For the non-arrested charged parties, I suppose an expert on international law and extraterritoriality could explain that there is no international law protecting people from charges for working in their own country to violate the laws of another country, though enforcement of those charges may be difficult so long as the charged parties remain in and protected by the government of China. But, I mean, it doesn’t really take an expert in international law and extraterritoriality to explain that, either.
So yes, the US also tries to exert power over people it considers American subjects well outside its jurisdiction.
That doesn't excuse China intimidating and threatening Chinese people living abroad, though.