Not that surprising when you consider that education may be more about the overall physical & social environment than the specific method. Despite the current fashion of doing a lot of hand-wringing over the fine points, kids are surprisingly indestructible and will generally turn out pretty well if the environment is basically sound or even if it's not-so. This is consistent with millions of years of evolution during which there was no institutional education at all. Basically a child learns the truth about whatever environment they're in, and adapts to it. So yeah, there are for example, truly fucked-up environments where a kid learns all the wrong lessons about life... but notice, they do learn them. To the degree that they manage to find similarly fucked-up environments to inhabit as adults (criminal gangs let's say) they will thrive. Meanwhile if a child is in an environment where there is mutual concern/care and a curiosity for learning, they will learn and adapt to that. Adults don't make that learning happen though; they only create the environment. They have some control but not nearly as much as they think. The point of Montessori seems to be to explicitly take the adults out of the picture a little bit more, which is just acknowledging reality - they're already mostly out of the picture. EXCEPT in their capacity as establishers of the overall environment, and I don't see nearly as much variation there.