When I went ~5 years ago, I was completely unable to use the taxi apps due to lack of Korean bank acct. This lead to being unable to even hail a cab at times - they mostly seemed to pick up fares from the apps. At one point I managed to get one of their attentions - and was told that he wouldn’t drive me because I was an “outsider”. Not sure if he was actually xenophobic, didn’t want to deal with a cash fare, didn’t want to deal with my lack of Korean, or just had a misunderstanding. A later “successful” cab ride put me going halfway across the city through the mountain. I had to call a date I’d had and get her to explain to the driver that we were going the wrong way. The perils of going to new country underprepared I suppose.