China's system is not much of value in comparison. UC's problem is that there is no verification on acquired knowledge. Not standard test. You can have non standard test on how much and how well someone learned the knowledge.

> One billion people

If you referring to people who take the exam, it's 10.78M [1].

> One standardized metric to determine who goes where.

This is just to determine the entrance to public university. Of course, the people who can afford alternative higher education is negligible compared to those taking gaokao.

But there are actually a lot of people who won't take gaokao, as they entered vocational school, in 2019 6M entered the so-called vocational high school.

> Removing entry exam requirements does not help underprivileged students.

You got it wrong.

It's not about privilege it's about the effectiveness and efficiency of the talent selection. Secondary is about giving education as a means of climbing social ladder.

[1] https://3g.163.com/dy/article/GBTPVA0U0517M6OP.html?spss=ada...