It might be rare, but right now those engineers are super valuable, and are getting paid for it.
demand and supply.
you see the same thing happen with self driving engineers commanding million dollar packages because they were in such high demand and supply was so low.
They are super valuable now but their value will decrease as the Chinese semiconductor industry catches up, so it's not like TSMC will have to pay 2x the salary forever. However I know many people (not at TSMC) who would take a lower salary to work on green field projects.
What we're discussing is that it's hard for a company to pay the market rate when the competition is the CCP itself. The CCP would pay the equivalent of $20 million if it needed to - and what then?
Wherever the CEO and chairman's $10m annual package came from. You either pay market rate or risk your employees leaving.