It’s been stated that 工 asserts the sound こう when it’s used as a radical. I’m not sure if it’s every time. There are so many to look up that I didn’t want to bother. In any case, I’d noticed this with a few other radicals (traditional or not) as well:
Do you guys know of any other cases where this sound assertion is across every usage?
(I found this topic from 2015 discussing similar concepts:)