What in interesting question.
I would have thought it's up to parents to teach values and ethics, not schools. Am I naive?
True - but when you think about the amount of time kids spend at school you want them to be somewhere that aligns with the values you do teach.

I particularly liked DS's first school because they taught (what I considered) true independence. The clearly stated they didn't assume they know everything and gave kids the chance to follow their own learning path....unravel things at their own pace etc. They also didn't consider teachers or adults in general "higher" than the students. That is very important to me personally.

I found most schools gave the same spiel about teaching values, I was far more interested in HOW they taught that.