The culture over there makes a huge difference. I read on
wikipedia that the government tracks your cellphone and credit cards so that when a person tests positive, everyone else who was in reasonable contact to that person gets a text to notify them. That helps the contact tracing a bunch. There is a much larger % of Americans that would have a problem with that than the South Koreans.
Not saying right or wrong, just different cultures responding differently. Y'all can form your own opinions. I'm not sharing mine. Also those that test positive have to quarantine and download an app to confirm they don't leave their quarantine location. Not hard to work around that and I would appreciate measures to ensure known sick are abiding by quarantine but just the thought of the government requiring you to download an app to track you just because you are sick would bring about legal challenges. Although there are reported cases of police having to monitor covid19 positive Americans because they refused to abide by quarantine. Once again, more govt intrusion in SK but with measurable good affects to fight this coronavirus.
The other thing that has really helped SK with their response was the lessons they learned from SARS1. They had one of the worse outbreaks and they, appropriately, learned from this and stockpiled testing supplies and reagents for potential future outbreaks. They also had plans for contact tracing. They were prepared and adjusted swiftly to how SARS2 behaved vs SARS1. I wish all countries could've have learned from SK how to be prepared but hindsight is 20/20.