Like most everything contaminated by bureaucrats, the public school system has grown into an obese and ineffective institution, whose main purpose appears to be as a societal money pit (and governmental daycare). The curriculum reflects this. Instead of a focus on the essentials, the focus is on the ever more trivial, and considering the increasingly dismal test scores and dropout rate, the so-called teachers and admin cannot even manage to teach the irrelevant. And so the curriculum becomes as bloated as the budget.
Anything and everything that actually needs to be taught could easily be taught, within the confines of a six to eight hour school session, and without any need for homework. Well, it could if not for the bloated curriculum encompassing needless classes, and useless time fillers. I would bet the school day could even be shortened by at least a few hours if the teachers and admin were forced to learn effective time management, and were subject to streamlining by efficiency experts. No doubt the school budget could also be trimmed of excess fat by the same or similar means. Of course none of that will ever happen if the unions and other obstructionists can derail such reforms, and they always will, as they don't care about the future of the kids...only about maintaining their status quo.