Can you link the source for the flight hour difference?
If true it does have some signal but it’s not entirely persuasive. After all there clearly are midwit pilots too with a lot of flight hours, who just manage to scrape by on each step of the way.
Edit: Who may very well perform worse in extremus than a less experienced genius pilot.
Are you taking that number out of your arsenal or from a source? AFAIK most South Korean pilots are actually doing their training in the US, since it's much easier to accumulate the hours, and there's more GA. I would think their training is about the same as US pilots.
Although the US airways system is much more developed and used than Korea's, given that Korea is a smaller country and has an extensive bullet-train network. So I could buy an argument where US pilots just fly more.
Most flights in Korea are international flights, so a pilot for Korean air probably flies as much as a pilot in the states. If the airlines need fewer flights, they could just go with fewer pilots rather than the same number of pilots flying less.
In the 1990s Korea and Taiwan had issues with accidents caused by military pilots without modern crew management cultures (“never question the captain”, which is a big no in modern commercial aviation), so they went with more career pilots trained from scratch (at American schools) rather than just transitioning military pilots into the role.