I don't think you can really separate it out like that. It is part of what You Just Do At School, definitely, but it is also conveniently a cost-saving measure, sure. That doesn't mean that if you tried to cut it out, that parents wouldn't complain about it.

At any rate, having seen both, I assure you that there is infinitely more bullshit that American kids are doing at school instead of learning, compared to Japanese.