How did Korea control Covid-19?

How South Korea controlled the Wuhan coronavirus:

• Respond quickly. As soon as their first cases were confirmed, South Korea furiously manufactured test kits, and they now make more than 100,000 per day. They also immediately began tracing the contacts of infected people.
• Test, test, test.
• Trace contacts and isolate them. Don't wait for symptoms to appear; if someone has been near an infected person, isolate and test.
• Enlist the public's help. No scofflaws in Korea partying on the beach.

The result is that Korea has done better at controlling the virus than any other nation, despite an curve that at the start looked just like Iran's or Italy's.