I should preface my remarks by saying that my knowledge in this area is quite narrow. Although all of my children went to the local public school for part of their elementary education, they went to Montessori schools before entering public school (one, my most outside-the-lines child, was in Montessori through grade 4). However, for high school, they all went/are going to boarding school. They were never tested there and I think the reason is that private schools are judged, fairly or unfairly, by their results ... and for them the results are where do their graduates go to college. A private school that doesn't do well in that arena starts losing good applicants, the next graduating class doesn't do so well ... it's a spiral effect. What if schools were judged by how well their graduates performed in the various arenas they choose after high school?
Looking back at their years in the local public schools, the one criticism I have is how each year the testing crept more insidiously into the curriculum so that by my daughter's 8th grade, I was aware of important chunks of knowledge that were not taught because of the importance to the school district of doing well on the state wide California tests. Again, just my opinion. Janet