[jzwinck]

Moving between North and South Korea is restricted but not completely eliminated. There are people who legiimately work in one and live in the other (not just officials).

[samstave]

What kinds of jobs do those people hold?

[azernik]

If they're including old data, up to two years ago there were quite a few South Korean managers and engineers working at the Kaesong Industrial Zone (https://en.wikipedia.org/wiki/Kaesong_Industrial_Region)