Some of you may know about this particular situation, especially the lower down the racial ranking you may be. Sociologists have used something called a "social distance scale" to determine levels of peoples comfortableness with mingling with members of another race, especially when it came to whites and blacks during the 1960s and 70s. The scale kind of went in order of least to most comfortable, generally according to the categories of stranger, acquaintance, coworker, neighbor, a friend you would have over for dinner, or someone you would allow to marry into your family. You would rank members of the other race according to the categories, and it was a good way to see just what people meant by their willingness to accept "integration."
I just mention all this to set the stage. As it stands right now, no matter how much people talk about so-called "multiculturalism" in Korea and being receptive to people and ideas from other cultures, in reality and on the ground, I doubt most people in Korea would check any box higher than appointments or maybe coworker for a " foreigner." I recently did this experiment in my social issues class, and many of the Koreans in the class admitted that most people could not go past coworker, perhaps an English teacher an institute, and that is the best one might do if one is brown or black. The Koreans were all pretty much in agreement that most Koreans would not probably like a Nigerian family to move into their apartment complex, or that even a white coworker would possibly create a lot of tension.
And this seems to ring true on the bus. Basically, if you are a foreigner, and especially if you are dark and swarthy, people won't sit next to you, even on the most crowded bus where there's standing-room-only. It's actually pretty insulting, since what people are all saying is that they'd rather stand and then sit next to your inferior ass.
Knowing this, I have always stuck in a conundrum. Do I politely put my big bag in my lap and let the seat so empty, a constant reminder of how disgusting Korean people find me, or do I leave it there, and create the impression that I am a big, fat assh*le? I've been leaning on the side of the latter lately, since I am just sick of doing something charitable but made to feel stupid.
In the end, Korea is busy enjoying the fruits of consumable "multiculturalism:" nice Italian cuisine, Chilean wine, and the like. But deep dw, most Koreans don't even want to sit next to you on the bus.