You are completely wrong. Like I said in my other posting that ONLY during the first several years since 1977, city kids (who supposedly have better life) performed better than rural kids (who supposedly have hard life). Rural kids completely caught up and many out-performed the city kids, because they are more motivated and work harder than the spoiled city kids!
Don't forget that unlike Taiwan where I guess you have to pay for your after-school tutoring, in China students don't have to pay or pay very little for their education! Teachers including after school tutoring are paid by the government, not the students. But why do teachers and schools do that kind of work, such as after school tutoring? Both schools and teachers want the honors for producing more college-bound students and teachers get special bonus for producing college-bound students!
To be more exactly, when I was in China many years ago, all education were free for all at all level. Individual student's economic level did not really matter, although parents' education level do. But still it would not be the end of the world, if you don't have well educated parents. Because there are so many very dedicated Chinese teachers who will teach you or your kids regardless paid or not! As a daughter of poor city workers who had no any connection or money, I not only got all my normal education free, but also received free after-school tutoring at my high school by several teachers! When I was accepted by one of the most prestigious universities in China, my teachers and the school were absolutely excited. I later heard that all teachers who produced college-bound students received recognition and compensation. But no dime from my pocket.
As China's economic reform going further, the government changed some aspect of the all free education. Now city students (who supposedly have higher income) have to pay for books and materials, but not tuitions. It's still all free for country kids.