There is absolutely no question that SK's strict prevention measures are the cause of that. They were very strict from day one, no doubt because they were hit hard by SARS-CoV-1.
I lived in South Korea 2019-2021. On top of what you said above, they have a very good very intense contact tracing system, in SK the phone/bank/government are pretty inter-connected, it's not difficult for the government to literally hunt down cluster infections and force people into quarantine, and they did. They sent out over sms the exact times and locations of places people who had covid visited, etc, etc. I think contact tracing, Koreans taking it very seriously, wearing masks correctly, actually social distancing kept things under control. Koreans a very good at following instructions when they decide to, and they do it diligently.
The infection rate is also commensurate with general immune system fitness.
Remember in bad covid what we observe is vascular system failure, and we know that chronic hyperglycemia damages blood vessels. Combine that with non functional immune systems and this is what you get.
Switzerland has a higher life expectancy than South Korea, and has a very wealthy and healthy population.
Spain and Italy have both held the titles of "healthiest country in the world" in recent years.
All three have incidence rates more than an order of magnitude larger than South Korea.
Wearing respiratory protection equipment protects against respiratory contaminants. Testing people and tracing contacts helps to contain outbreaks. The answer is really that simple. South Korea was one of (if not) the first countries to start an aggressive testing and tracing program.
On TV, I watched their citizens line up in cars at mass testing sites months before my multi-billion-dollar healthcare conglomerate here in the US even had testing available at all.
That was only the first time, and only after the virus was everywhere. SK reacted much more rapidly when it initially came to them.
Furthermore, Schengen. SK are for all intents and purposes an island, and everything and everyone must come by either boat or plane, which helps with control.
It depends on the disease, covid is immensely correlated with diabetes / metabolic syndrome, which is rampant in many western countries with America at the top.
It's behavioural modification, and it actually works. The aim is to encourage people to do certain things. To that end, restricting various things which on their own seem nonsensical, actually becomes justified if it changes behaviour.
I happen to believe it's only optics, and frankly am disturbed to find myself in a fully postmodern society where only appearances and posturing matter.
What's not to understand? The numbers in Korea are low because everyone is willing to sacrifice their personal freedom and convenience for the common good. They vigilantly wear masks, socially distance, follow guidelines, and abstain from K-Pop dancing at gyms and running fast on the treadmill when their health departments ask that of them. Americans will happily let more people die if it means they get to go to the gym without a mask. It's really that simple.
I disagree, I think it was 95% being a de-facto island and shutting down international travel without aggressive quarantine upon arrival.
Why, you ask? Well I was living in Hawaii during the pandemic, we're Americans, and we had very similar results through the end of June 2020, nearly extirpated the virus in fact.
Unfortunately the US Military couldn't be compelled to follow restrictions, and a huge outbreak in Pearl Harbor escaped containment and ruined all that hard work.
You don't think it has anything to do with the awful physical and mental health of Americans, as opposed to not following the rules? And mind you, I'm not in American but in another western nation where I've observed with my own eyes that people have followed all the stupid rules, regardless of enthusiasm, but they respected them, and the outcome has been just as disproportionately bad.
I spent last December in London and saw scant respect for the rules during the second wave. A minority of people wore masks, and few of those wore them properly. I was invited to a few house parties and festive gatherings.
Then I spent January in Paris IIIe where mask compliance was much better, but the streets and supermarkets were heaving before the daily curfew. Squeezing down aisles to buy supplies for dinner. Friends publicly complied with the rules but had big house parties every weekend.
I departed in shock and with an understanding of the European case numbers. There was no discipline, everyone seemed too fed up and bored to care anymore. Abstract anonymous others be damned.
Returning to zeroth world east Asia was a relief. Everyone, and I mean 100% of everyone, wears masks properly.
That originally happened before any official requirement. People go out when there are zero cases, but when a community transmission case happens the streets go quiet for a while, cases disappear, then nearly normal life resumes.
While health might play a part, discipline, a sense of community respect, and a competent administration seem far more important.