the hierarchy is a big thing everywhere in Korea, not just schools. I think it all comes from that. I also feel like bullying like that occurs everywhere in the world, but it is just not as medialized, dealt with in the same way aka "ruining your career later". In Korea it seems like the whole country basically runs on the survival of the fittest - you have to be the prettiest, the cleverest, the richest which is something the new "hip" youth strive to drive away from. In the West and the Americas, youth tends to find happiness in the nature or themselves while in Korea it is still hard work, good grades and perfectionism. The amount of stress the kids are under create frustrated, emotionally constipated monsters who are happy to meet a person "who is somehow less" than them and enjoy that superiority feeling to the fullest.
still, I don´t think the Korean schools are the worst of the worsts. I have actually read a review of a British-Korean who said unless you attend tons of classes at cram schools and your parents are devils who push you to the fullest, life is good and Korean children don´t get significantly more homework than others (which is based on an experience of one person, fair enough). the real hell of Korean education starts in high school which is severe because it is a very old-school system based on memorisation (something that a lot of countries try to run away from) and I really don´t envy that the high schoolers.
thank you if you have read my thoughts so far :D. all I have wanted to say... I don´t think their schools are that bad or that there is more bullying, I just think it is more medialised and can be used for further damage