India graduates good math and CS students from IIT, why is India not an engineering excellence hub?
Because they come to the US. US STEM grad schools are full of students from China and India.
I have interviewed many, many people and am usually quite impressed with the Russians interviewed. They usually do much better than American-born people. Maybe 1 out of 6 non-Russians are decent, the Russian batting average in my experience is 1 out of 2 or even 2 out of 3.
They do make good engineers, the problem for those countries is the good engineers move to the US where they can make money.
I read somewhere that many of the most successful entrepreneurs in the US are foreign born. That doesn't necessarily mean that foreign born people are better than American born people (which would be unlikely). It probably just means that people who have tenacity to immigrate also have tenacity to do bigger things than average.