“English Teacher wanted, good salary, Americans/Canadians only”
Even now, if you browse a job forum you’re bound to find an employment advert like this and shouldn’t be surprised by it. There is a tendency in Korea to be favourably bias towards North American English and thus North American teachers.
Some background on this:
Like so many Asian countries, Korea borrows certain cultural elements from the United States. One of these includes an accent. The first time I heard a Korean English accent it sounded like a mixture of a Hollywood star and the girl who owned the Chinese shop next to my house. In fact, I thought the woman had learned to speak English from watching Brad Pitt movies!
Now I don’t want to suggest that all Koreans try and sound American (either deliberately or subconsciously), because some Koreans do not sound American at all. Many study English in other Asian countries or Australia and maintain their unique Asian English accent. But in general there does seem to be a tendency to be drawn to things American, including American English. You can hardly blame them when it is after all the same country that saved them from communist invasion in the 1950’s.
British English (which is what I personally grew up with) is not popular in Korea and most Koreans won’t know alternative British spelling for words (like s replacing z in analyse) or have difficulty understanding stronger British accents.