They Did Not Have Enough Korean Actors
When the series was ongoing, there was not a big talent pool of Korean stars in the industry. This was the reason the producers often cast actors and actresses of other Asian ethnicities to play those roles.

They Did Not Have Enough Korean Actors
A Real Korean Actor On The Set
In fact, there was really only one true Korean performer on the show: Soon Tek Oh. He played several roles in the show. He was a big star from the ‘60s and stayed active in the business until his retirement in 2006. The photo is a still from Charlie’s Angels. He died in 2018 at only 85 years old.

A Real Korean Actor On The Set