I doubt these North Koreans are getting hired due to wage disparities (these are roles supposed to be in the US where they have a contact person in the US), more like they have perfected the interview process as the most important thing in their life.
I got the impression from the article he was working with people in Turkey and Hungary to use their identities to get jobs in the UK and US. So US company found this amazing Hungarian dev who would work for 1/5 what an American would ask for, but they paid for it either way their privacy (hey wait a minute, sounds familiar...)
https://news.ycombinator.com/newsguidelines.html