I've witnessed the Chinese judicial system secondhand, as experienced by native Chinese people. Fortunately, I haven't had to experience anything firsthand. And I've read countless articles and books to the point where I know the specific incidents those signs are referring to.
I'm sorry, but I really can't spend any more time digging up sources for you. Hopefully you have a VPN or live abroad and can look for this stuff yourself.
You can probably understand why they wouldn't want to be subject to that justice system.
You keep putting words in mine and other people's mouths. I never said democracy is a panacea. I agree that Western media is biased about China. Average people are not well-informed anywhere. At least outside of China, people can easily learn if they choose to.
I agree that Japanese politicians downplaying or refusing to apologise for Nanjing is somewhat comparable to the CCPs handling of the Tiananmen incident, although Japan obviously has nothing like the censorship in China. Both are wrong. And I think if you talk to more people you'll find they agree.