It's also not one exam, in the sense that it gets held multiple times a year and retaking it (if you're willing to pay for it) is possible and a lot of people do it and submit their best scores.

The SAT & ACT are also mostly limited to the humanities and math (and science for the ACT), with an optional writing section. China requires Math, Chinese, a foreign language, and any three of Physics, Chemistry, Biology, Geography, Politics, and History. With the SAT all those elective subjects are separate exams and most people do not take them.