The "work" Visa stamp in my passport was proof enough that I was approved and sanctioned by the South Korean government to teach English. That stamp was all that I thought I needed. Admittedly, I had no degree (yet), I had no formal training in teaching or English conversation, no TESOL/TEFL experience, and I hadn't even taken any college courses on teaching. At the time it never even occurred to me that one might need, or even want those things, in order to teach English in Korea. Mr. 신 never mentioned any of that either. But I did have the government stamp:
However, relative to the college kids who were paying to learn from me, I certainly was an SME (subject matter expert). And generally speaking that is enough to warrant getting paid. At least in corporate America. I have worked with many highly paid folks who never even made it to university. But by today's standards for English teachers in Korea I probably would have been considered "unqualified."