Asian countries especially China have better STEM education than any other country bar none. They just have that drive to survive - success is another story when you are competing against a billion or so other chinese STEM driven students. Their instinct to survive is just crazy...it's the culture and you can't compare that to the USA at all.
China is not a homogeneous country and they have huge number of poor people. They also have a growing middle-class and wealthy segments too. Not every kids is a STEM genius and there are reasons why a lot of Chinese want to raise their kids in the United States instead of China. And lots of them move here, set up households and raise them here.
I think that Singapore does far better than China at STEM education in general but that's partly due to the parents. I think that Finland does a pretty good job too.
But China has the numbers. If you take the kids with aptitude, then China has more because they have a much bigger population. There are all kinds of problems with Chinese education - they are not the Master Race that you make them out to be.