There are probably a hundred people who have written answers, but please bear with me. Children with autism learn much, much less from the environment.
ABA is all about the rules for setting up the environment to enable our kids to learn.
This is accepted by everyone who wants to train their dog to 'go' outside, but we are not so inclined to want to believe the same of ourselves. These are the basics of learning theory. ABA uses these principles to set up an environment in which our kids learn as much as they can as quickly as possible. Behavioral learning is not the only type of learning. Most learning in schools is from an explanation or from a model, what people call 'natural' learning.