It self-selects some of those families. It also self-selects a lot of families who are paranoid about secular education or fail to understand the value of education at all or of having teachers who know their subjects well and are trained in educational theory and teaching methods.

Probably the homeschoolers on this site largely fall into the former category. The stories you hear from a broader cross section online of home-schooled kids skew heavily toward the latter.

As well as families that disagree with the politics and curriculum their public schools practice...