Well that’s a dumb question
That was kind of my kneejerk reaction too, but…there’s a relevant xkcd:

No matter how common-knowledge something might seem to a given person at a given point in their life, they weren’t born knowing it. Everything I know is based on my experience in life. And for every bit of knowledge, there was a first time I saw it.
Every person needs to have that first time for every piece of knowledge they pick up.
Psh, everyone knows about that relevant XKCD

In a word: authoritarianism.
In several more words: because the Chinese government is simultaneously hyper authoritarian and EXTREMELY thin skinned about any criticism or gainsaying of the official narratives.
Are there authoritarian governments who aren’t thin skinned? As far as I know, power projection at every level is their usual mode of operations, as everything else could be seen as weakness by their followers.
Really, it’s the protesters fault for wanting human rights. /s
Central to the case was the organisation’s longstanding slogan calling to “end one-party” system in China.
Hate articles that have a title as a question and you have to go dive for the answer
Apparently not related to the vigils?
Every June 4, crowds gathered in the city’s Victoria Park for a candlelight vigil commemorating those killed and demanding accountability from Beijing. At their height, the commemorations drew crowds numbering in the tens of thousands.
or they would put thousands on trials not just the two?






