I don't think it's true that the Gaokao is regarded as a great equalizer. You might be misled by the fact that it is regarded as the only potential path out of rural poverty in China - but even in the wikipedia article you link it discusses many of the issues with it. And this (2014) NYT opinion piece covers some in more detail (including that yes, richer students also spend time after school preparing). https://www.nytimes.com/2014/09/05/opinion/sunday/chinas-edu...