For example they are not allowed to teach calculus, despite calculus making the tests easier, for the exact reason public schools do not introduce it in the standard curriculum. Instead the schools are places to drill test taking and memorize tricks to be used on said single exam.
It is an entire industry geared to a single once per year test. Every dollar spent targeting said test is an economic loss. It is the exact sort of economic loss one should expect from perverse incentives. Banning this industry papers over the symptoms of a broken system, it is an obvious move but not a brilliant one.
Shanghai was leading the way. They gave individual teachers more freedom that allows move away from rote learning (taking lessons from Nordic countries). They also increased teachers’ pay. The results have been amazing. Shanghai ranked first in OECD PISA 2009 and 2012 assessments.
In the latest 2018 assessments Bejing-Shanghai-Jiangsu-Zhejiang areas ranked first. Rest of the China is still behind.
Why don't they teach calculus, i'm genuinely interested, you've left us hanging!
Edit: thinking on it a little, I'm guessing the missing sentence is 'because such calculus is not on the test'.
The tests are not easy, and the "passing score" is set by the sum of competition. The techniques allowed to be taught, and which get tested are obtuse. Instead of allowing brilliant students to progress into more difficult subjects the tests funnel the entire country into the same testing flow. It would be like trying to score everyone based on arithmetic.
Yes arithmetic is easy, but given enough volume of overly complex questions even easy skills can be tortured to create a grading curve.
Have you never had a great lecturer who can deliver information in a way which makes more sense to you then just reading it off a website?
Eventually this is a lazy mechanism to select prospective students to a course. The purpose of the course is to prepare people to build an air plane or be a good doctor, historian, architect, journalist or whatever. Not be good at exams and interviews.
When you make testing all about gatekeeping, wikis don't help, because the questions are not about test of knowledge of skill.
If you have a pervasive cram school culture in your country, eventually you have to import/buy from other people because your people are considered on-paper geniuses but are not good at any thing apart from acing testing.
I guess for where China stands now. Making chips, airplanes and space stations needs the real engineers not just the ones who can score well in exams.
Edited: I'm talking specifically about Chinese tutoring industry. One comment below gives a very detailed description, which perfectly explains why I think it's worthless. We are all in the process of a revolution initiated by wiki/scihub/libgen. Whether agree with me or not, you are welcome.