I agree that poor belaying is a result of poor education in techniue and safety...but also because "experienced climbers" often get lax and lazy. Beyaing 20 odd feet from the wall is a typical example and to be fair not unique to Korea at all. We see it here mostly because we are here now. It's very hard/ awkward/ risky to try and correct a locals bad habits anywhere in the world...so try the teaching without words technique...by example and by obviously instructing your partner in what not to do (so that anyone watching will see, understand and 'get the message' without being directly addressed).
quem deus perdere vult, primus dementat