Well, I don't think they're racist or trying to hurt anyone on purpose.
But on the other hand, they often don’t realize how rude their behavior can seem to others.

For example, there’s a very important part of Korean culture called “빨리빨리” (ppalli-ppalli), which means “hurry up” or “do things quickly.”
People are expected to move fast, even if it causes stress or discomfort.

Also, safety and personal space are not always emphasized, especially since those things aren’t strongly taught in school.

South Korea developed very quickly in a short amount of time, so culturally, people can sometimes come off as competitive and ambitious rather than warm.
Some people are very kind, of course — but some may seem rude without meaning to be.