>For 2012, the US Department of Justice reported a 93% conviction rate.

Japan also looks like it has a 99% conviction rate. Most countries have the ability to exit-ban foreigners visiting their country. It's not unique to China at all. US does it. Canada does it. South Korea does it.

I think the warning from the US Government is that, in their opinion, China will illegally detain you over made up charges, be careful.