As a general rule, Koreans don't think it's necessary to say "excuse me" if there is incidental bumping on a crowded street, bus, or subway. Fair enough, I suppose - and I've been here long enough now that I don't get really angry when someone cuts me off. The one exception to the rule for me is people trying to get on the train when I'm trying to get off. It's then that the Davey elbows come out, and for most Koreans, my elbows are at about eye-level.
Anyway, as unnecessary as it may seem to most Koreans to to say "excuse me", there are times when it would help.
For instance, coming home on the train tonight (line #4), doors opened at a stop about 5 from where I get off. The train wasn't too busy - there were plenty of seats available, and there were two teenage girls and one older lady standing up near-ish the door. The doors had been open for about 4 seconds (which, in Korea, is a long time). A woman who had fallen asleep on the bench suddenly sprang-up and charged for the door, probably realizing that we were indeed at her stop. She plowed directly into the middle of the two girls (Ka-BAM!), sending one flying into the upright bar near the end seat, and sending the other into the elderly lady standing on the other side.
What I'm talking about is roughly this...
Only imagine the two pins a little further toward the center.
There was not one word from the charging ajuma - just a bone-crunching running panic as she awoke seconds late for her stop. Not a word from the others who had been plowed into either.
Someone recently explained the reasoning behind the phenomena this way: "We can't be angry at them because we think that someday, we will need to do the same thing, so we will expect their kindness as well."
Not sure if I think that's a reasonable excuse for what, to my eyes, still adds-up to unnecessary rudeness.
Then again, if that had happened in Calgary and the girls being plowed into were a little on the rougher side, that ajuma would probably at least have a broken nose, if not dead and lying in a growing pool of her own blood.