Let me start off by asking if either yourself or GP have kids of your own, and just mention for a short moment, talking about how hypocritical parents are, while judging them while not having kids of your own, well...
The fact is, kids take up a lot of your time, and I mean really a lot. No you are not prepared for how much of your time kids take up. While you decided to have kids, you still have hopes and ambitions of your own, and would still like to be the master of how you spend your own time to some degree.
So in order for sanity to prevail, and for parents to be able to work a job and not have to look after their kids the whole time, society created the schooling system. This systems main purpose is to take care of the children while the parents can earn an income, and the secondary purpose is to provide an education while looking after the kids.
Can this system be optimised? Sure. But who has time? Certainly not the parents.
And the points I am making above, are being realised by a hell of a lot of parents trying to work from home while having to home school the kids at the same time...