Generally, people prefer their own ethnicity (not necessarily race) over other races / ethnicities. Someone looking to branch out will either look towards others of their own race, or white people. So many Koreans may well prefer whites to, say, Vietnamese. White is the ‘exotic’ option.
In most parts of the world, white people are seen as safe, rich, and polite. They are seen as having good families and never wanting for money. The white people they encounter usually were able to purchase a plane ticket, take time off of work, and spend time soaking in their local culture.
Other races, when they travel, are not given the same appreciation. I was hanging out with some folks from my country that I met in the country I was traveling. I was white, they weren’t. When we would run into local girls, those girls would usually visibly indicate their preference for me. Nothing else mattered, they knew the local language better, they had more money than me. It was more of a pain than you would think, I like a little bit of a chase, and my new would-be friends weren’t too happy with my handling of the situation.
I imagine it would be most the same wherever I go.