I read this book “Methland», about the use of the drug in the deindustrialized Midwest. A lot of the people who used it did it to be able to work long shifts (they had to work a lot, because the hourly wages were so low). That may be the case for North Korea as well. If you have to toil long hours in the field without proper nourishment then meth will of course look like a good deal.
Damn, whatever happened to Red Bull?
I'm not sure, because I would assume they also sell it in rural Iowa and Illinois. It might be a bit trickier to get in North Koreah though.