Anecdata, however: project-based learning is powerful because getting something to work brings pleasure and failing to make it work brings pain. Being able to manage cycles of pain-pleasure from various stages of building and refactoring a project (hardware can also be refactored) is the basis of learning.

Schools don't teach project-based learning because schools are not interested in learning; they are interested in child-rearing, not letting them kill each other while the parents are at work, and offering employment for teachers and administrators. In schools, generally, learning is an epiphenomenon, not even an afterthought, simply an accidental side effect.