To understand this question, you have to go back to the nature of the people in each country. cultures are different. People react differently no matter where you go.
To begin with, the S. Koreans have been used to wearing those masks for a long, long time. Whenever one of them gets sick, they put on a mask so as not to infect the others. They also wear the masks every spring because of the yellow dust that floats into S. Korea from China. Foreigners who come into S. Korea and are not used to the yellow dust very often get extremely sick the first year because of that yellow dust, but S. Koreans know how to prevent getting sick. They have been wearing those masks a long time. New Yorkers didn’t wear masks initially. It is just not part of the American culture to wear those masks. Americans didn’t even know if they would do any good. Americans had to learn about the masks during this pandemic.
Another reason that less Koreans got sick is because S. Koreans are much more diligent about their health than Americans are. Some Americans encountering the S. Koreans for the first time might think they are hypochondriacs or finicky. The minute a S. Korean gets the least bit of a sniffle, they head for the doctor’s office. Americans don’t do that at all. In fact, many of us don’t do anything about a cold except just live with it until it goes away. We don’t see a doctor as often, and we go ahead about our lives as if nothing is wrong even though we feel bad. My dad was a really tough guy, and he raised me to be tough, and there are many Americans like me. My dad taught me to ignore my physical problems and just keep pushing through. Many Americans are like me. Many Americans just don’t see a doctor until they are half dead. On top of that, it is much cheaper to see a doctor in S. Korea than it is in America. Even if you don’t have medical insurance in S. Korea, it is cheaper to see a doctor than if you are in America and have medical insurance.
I saw videos of New York City, and when they tried to quarantine them. people didn’t listen. the busses and subways were still full. However, I saw pictures of Seoul, S. Korea, and they were not under quarantine, but the subways were empty. Those S. Koreans are going to protect their health. That is all there is to it! S. Koreans are overall healthier than Americans because they are extremely diligent about their health.
Another reason could also be the cultural acceptance of the proximity of the people. Every culture is a bit different as to how close they let the others get. In Nigeria, I was shocked to get in one of their taxis, and it was crammed with people almost sitting on top of one another. Nigerians will get closer to one another more than any country I have seen. In Europe, in many countries, they greet one another kissing one another on the cheek, but Americans would never do that. We are more likely to stand back and shake their hand. South Koreans stand back even more than Americans do. The Koreans are more likely to bow as a gesture rather than shake hands even though they also shake hands. The American guys move in on women, putting their arm around them as they walk, but you never see a S. Korean guy do that. There is also more hugging going on in America than in S. Korea. The younger Korean men are trying to learn to date like Americans and are learning to hold hands with girls, but the older generation often had only met their wives once before they got married, and some of them never even struck up a friendship even though they had kids together. They live in the same house, but the wife goes her way, and the husband goes his way. That would be grounds for divorce in America. The older Korean guys make friends with women they aren’t married to, but it is only a plutonic friendship. There is no touching.
Different cultures just do things differently. This caused the coronavirus to be able to travel easier from person to person in some places, and in other places, it didn’t travel so easily. There could be other factors involved, but culture is probably the biggest cause. In S. Korea, they only quarantined one city, the city where the virus initially showed up, but they didn’t have to quarantine them. In America, they quarantined everyone because we interact physically more than the S. Korean do, but it didn’t always do them any good. The S. Korean are much more docile than the Americans. If you suggest to a S. Korean that it isn’t a good idea to go out, he probably won’t. However, if you say that to an American, his response is usually, “I am an adult, and I will do what I want!” Americans are by nature more rebellious and harder than S. Koreans. That is what it took to built America out of the wilderness.