The public education system we currently know has been around for more than 150 years. However, the basic schooling model remains the same. Roughly 20 to 30 kids of the same age are stuffed into a classroom and taught by one teacher.
Even though the curricula have developed, the essence has stayed the same. Children are still taught in a standardized and industrialized way. As with anything that comes from centralized control, it is highly inefficient, bureaucratic, and wasteful.