The "Swastika" is first and foremost a Buddhist symbol in Asia. German Nazis don't own it.
Plus, tbh that mannequin was quite tall, I doubt Sowon had a good view on the hat and the tiny symbol on it. Plus, nobody pays attention to everything all the time. She was most likely just bored, waiting for the photoshoot (or whatever thing they had on schedule) to happen.
So in short, don't be so entitled.
Ok let's call her just dumb then. Even tho she goes to a Uni where you have to take an exam which includes world history. I wonder if she bought her way to the university