In what seems like a previous life I used to work out of the Old Bailey as a press photographer.I would struggle to tell many Koreans apart, they might say the same about westerners. Not sure this is necessarily racist? Maybe something about pattern recognition and the human brain.
I remember a case where one of the witnesses was a Chinese bloke who had seen a murder in Chinatown. When asked if he could definitely identify the perpetrator as the accused in the dock, he caused a stir because he replied that maybe not, as all Caucasians looked alike to him.
It's certainly "a thing", known as the "Other Race Effect". There's an episode of The Good Wife that centres on just this issue.
'They All Look Alike': The Other-Race Effect