Most "beginner"-level students at the university aren't actual beginners when it comes to learning English. The technical term for such people, in linguistics, is "false beginner," i.e., someone at a low level who has already had experience in learning the target language. Textbook design usually reflects this: I've never taught a single "beginner"-level class in which the textbooks begin with the ABCs, pictures of basic common nouns, etc.
I get the feeling that most Korean students, when they start learning English, first learn it from Korean English teachers (1) whose own English is barely functional, and (2) who teach English in the regimented Korean way, i.e., via rote repetition, memorization, and other methods that don't involve much thinking and/or creativity. While some foreign teachers come into the picture as early as elementary school, most of us expats get involved in the Korean students' learning process around, oh, middle school or so.*
One reader critiqued me when I had written an earlier post questioning an English teacher's competence in English. My critic's questions implied his own belief that a teacher's competence in English isn't related to his competence in teaching English. I can somewhat see his point: after all, it's easy to imagine a teacher who is extremely proficient in English, yet whose teaching ability is garbage. At the same time, though, I think a teacher with a shaky knowledge of the subject he's teaching is more likely to teach that subject badly: that, too, strikes me as axiomatic.
But back to false beginners. I've never had to teach a class from the ABCs on up, nor have I ever had to design such a curriculum. At my second job, the Golden Goose, we design "beginner"-level textbooks that are way, way higher in difficulty than "A, B, C, 1, 2, 3." There's an assumption, at least in the Korean wing of the English-teaching business, that all students of a certain age can be safely rated as false beginners. One of my Golden Goose coworkers thinks this has something to do with parental expectations: design a textbook that seems too easy, and parents get antsy that their kids aren't learning enough. This is a shame, because most false beginners are still missing a raft of basic English skills that they really ought to work on before ratcheting up to the next level.
*I'm willing to revise this observation pending demographic stats that show that most expat English teachers teach at the elementary level. I'm pretty sure that's not the case, however, despite the rumor, current among expats, that most of the money to be had is at the elementary level. Show me the stats.