In a culture with a high Power Distance Index, it is inappropriate for a subordinate to directly confront their superior. In the case of Korean Airlines, plane crashes have been attributed to the captain making a mistake and the first officer or flight engineer not directly confronting the captain, leading to the crash. (This has also happened in cultures with a high Equality / Egality orientation, for example the crash of the Air Florida flight in Washington DC in 1982 can in part be attribute to this same reluctance of a subordinate to directly confront a superior, even though both members of the flight crew were Americans.)
As for Korean Air, they did change their culture. This was done in part by making English the official language of flight crews. This change in language, along with other training, enabled the crews to be more direct with their captains, significantly improving their safety record.