It's the same reason you see keyword posters in math education. "Together" means "plus", that kind of thing. It's completely worthless, except for one-step problems, and even then it doesn't always work. What is happening is collusion between teachers and testmakers. You can't teach understanding, but you can teach test-passing techniques because the way the test is set permits this.

You see the same thing here, in English you can get away with not teaching quality writing if you teach techniques to score well.