"Teaching to the test" generally doesn't mean covering the material that the test is intended to cover in theory, it means drilling the exact format of questions, studying previous years, knowing exactly what you can sacrifice coverage of, how to guess multiple choice questions when you don't know the answer etc. Basically over-optimizing to fit an imperfect model.

Now, I'm a good test taker generally, and it has always helped me in life, and I will ensure my children know the rules of the game. But from the perspective of the country or planet, that's not time and effort well spent, it's a zero-sum arms-race that could have been better spent.

There's more to this, e.g. the fact that the tests are really testing the teachers (again very imperfectly), that some people want to privatize education and so on, but "teaching to the test" is a well known anti-pattern for good reasons, even though the individual incentives push us in that direction.