Not true, when was the last time you were in a classroom? 60% of the time is spent on non-educational activities or administration of the classroom or non-essentials. When they are studying the curriculum is dumbed down to the point of ridiculous. Thus 80% of graduated students do not have the most rudimentary knowledge of the subjects you pointed out in your first two paragraphs. Government schools do not work and waste time and money.
Look at the statistics of illiteracy, history testing and math testing among seniors. The statistics are reprehensible and those numbers are propped up by "part-time" students (Home Schooled students who take one or two classes at the high school yet whose entire scores effect the schools average) The majority of PS graduates do not know who wrote the Declaration of Independence or even who it was a declaration of independence from. And Math, do you know where the US ranks in math scores?
Science? Do you know the stories of education of times greatest scientist? Edison, Einstein, Franklin and others, how did they "learn". Do you know where the US stands on basic physical science?
Do you know the number of students that must take basic classes at a community college in order to gain full entrance? Public schools back then, as now, were run by local authorities. Schools are as close to the people as any institution in American life.
You obviously have no idea how schools are run or funded. All rules, regulations, curriculum and policies are handed down by either the state or federal government. Parents can have a choice.....of options approved by the Government. There can be no defense of Government schools of today. They are complete and total failures as proven by their own testing and the results shown by seniors.
I would however possibly endorse public education strictly on a state level (the federal government has no constitutional place in education) if it was:
A purely Classical education (prep school/private school style), no fluff, no "social programs", no religious exceptions
Run by local school boards consisting of citizens only, no bureaucrats
Voluntary
Parents responsibility
Without homework
Strict and Exclusionary - Violence, drugs and other non-academic activities will be prosecuted by the police if crimes or and if not an immediate cause of expulsion.