[alephnerd]

Because it's an afterthought.

Netflix added KDramas in order to help it pivot into the Asian market. Most viewers will be watching the shows via subtitles.

[matthewdgreen]

The shows are heavily promoted here in the US, and they default to the English soundtrack.

[alephnerd]

I'm in the US. And KDramas don't show up prominently in my recommendations (I prefer watching on KissAsian - force of habit and the subs are better).

The algo is heavily targeted to your own assumed tastes. The one time I did watch one, it was in Korean with English subs.

Maybe you watched a western marketed KDrama like Squid Games? Try watching Beyond Evil, Itaewon Class, Reply 1988, or Mr Queen and see if it reverts to English. I'm kinda curious now