they're still cheaper than US labour. And their supply chain has proxity benefits that the US no longer has.

And the workforce is reasonably skilled now after a few decades of these skilled labour jobs (watch some YT video of how electronics are assembled there, if you want to see skill).

In cheaper production countries, you'd see similar, but china still has the edge. That's why the higher cost (compared to yester-decade) is not a factor yet, and only some of the manufacturing is being pushed out to places like vietnam, but not all.

The advantage china has is a similar type of advantage that silicon valley has for tech.