If the only goal is to get our kids into shape for military service but is not military service in itself, what’s stopping us from doing this?
The goal is to make them fit for military service *prior* to their service itself. The better quality the recruits, the better the trainees, with much less need for *remedial* training, that basic training is not really designed to do.
A practical goal is to make the pre-camp recruits *better* than the typical recruits, so the word gets out that pre-training is the way to go for the majority.
Eventually, pre-camp can be improved by making up for missing schooling, such as literacy, and then can even incorporate classrooms for things like military history, culture and traditions. Subjects that normally take years to learn, if at all, when on active duty.