If I had to take a guess, Asia has always focused more on math in education than the US. Given that AI/machine learning is a lot of math it makes sense (they would have a larger talent pool for building the algorithms), but that's just one guess...
A lot of those are employed by US based companies and US still can outpay companies in RoW. The only thing limiting is access to H1B visas, so I doubt talent pool is the cause here.
But I would argue that designing an algorithm that appeals to the human psyche in the way that Bytedance as done requires more than math skills. Designing the TikTok "For You Page" is not a pure ML problem, its a people problem that is being solved with ML.
Personally I felt the appeal of TikTok is that the design is ML-centric - clean buttons, very clear signal, not a bunch of mixed feedback signals like in other apps. Everyone on board seems to understand the importance of the underlying ranking algorithm
