Bear in mind that those countries are demonstrably not forthcoming with their actual incarceration rates. China especially—a lot of people know someone who was carted off for a short stay because they were heard saying the wrong thing or they posted the wrong thing online. They eventually show back up one day and everyone tries to pretend nothing ever happened.

These are "administrative" detentions, usually short and informal, not officially tracked but come with long-term consequences of reduced employment opportunities and restrictions on ability to travel.

And it's a bit crazy because usually no one knows what happened to you during this time. You get arrested, they don't have to tell you what for, but they threaten you with long term actual prison time unless you confess to something. Then there's no trial, no sentencing, just an immediate stay in a detention center for some time until they decide you're allowed to leave.

The other part of it is that China doesn't jump to jail time for a lot of things that the US would lock you up for. Robbery? Pay the victim, no jail. Assault? Pay the victim, no jail. Rape? Pay the victim, no jail. If the crime is "private" or "personal" in nature, they prefer to treat it more as a lawsuit. It's only when you do things that oppose authority or social order that get you "disappeared."

And for some serious crimes like possession of drugs, murder, or counter-revolutionary activities, they'll just sentence you to death, which is also not reported and does not come with any prison stay as it would in the US. The rate at which this occurs is estimated to be incredibly high but is not reported in any fashion.

So one day a family member just disappears, you don't know why, but you hope they just return eventually after a short stay in a detention center. But sometimes they don't.