Who cares? You're dealing with millions of school kids every year, and need aggregatable data to make important policy decisions about how education is done. As

Who cares? You're dealing with millions of school kids every year, and need aggregatable data to make important policy decisions about how education is done. As long as it correlates well, it's easy to collect, and can be trusted not to be manipulated for bad incentives like this article implies is happening, we use it.