The people who manage to escape NK are a pretty good source

Journalists pay defectors for stories. No effort is made to verify anything they say. This practice is considered wildly unethical in any other context. They're not credible. But just the content should be enough, do you really think North Koreans pull trains from city to city? That the children eat rats who eat children? That they build fake towns with fake schools, presumably the fields are tended by fake farmers?

It’s perfectly possible for both the US and NK to be in the wrong.

So why aren't you asking why the US is allowed to participate when they commit far worse atrocities?