Assuming there is sanity behind the standardized testing.
In general, home schooling, which doesn’t need to use many standards beyond which the parents choose, has been shown to lead to objectively better results in earthly competition. There are a number of variables in this picture.
Even without sanity (which would definitely be preferable), ANY standardized tests let parents compare the performance of their child with the performance of other students across the nation. If children in my town score an average of 30/100 on ANY test, while children in neighboring areas (or even states) are scoring 60/100, then the lies are exposed.