I typically use the term “bae-geen” for whites and mi-guk sa-ram for everyone else.

So we European-Americans aren’t American?

Korean just doesn’t have a generic word to refer to non-Koreans yet, although it should.

It doesn’t need one. Koreans can do as English speakers do and refer to people by their nationaliies if known.

She should have been taught better by someone in-the-know. Why not call them “colleagues?” Would that be so hard?

It seems Korean nationals always have to make the distinction.

It really wouldn’t be that hard for these people to not say foreigner all the either.

They could say, “the person in the red shirt” or something else.

I’m mean if I go back home and start calling Koreans “immigrants” what would people think?

Korean just doesn’t have a generic word to refer to non-Koreans yet, although it should.

You are correct. The problem is that Koreans use the English word “foreigner” in the same way. In a number of conversations, Koreans have described experiences in foreign countries, referring to locals as “foreigners.” Koreans will identify non-Koreans as 외국인 or foreigners even when the nationality is known. For example:

Korean: While in Australia, I traded music with a foreigner.

Me: What country was the foreigner from?

Korean: He was Australian.

Me: Well, why didn’t you call him an Australian instead of a foreigner?

Korean: (blank look)

It’s isn’t just a difference in usage, but a whole mindset and worldview behind that usage, which Koreans usually carry over into English.

“ps: Korea really does need to invent a few more, nuanced words instead of using “foreigner” for any Notkorean, wherever they may be found.”

She almost certainly did not use the English word ‘foreigner’. The default meaning of the Korean word 외국인 is someone from outside Korea, even when the speaker is outside Korea.