Yay for you. You were so smart reading, writing, and doing long division at kindergarten age. If only everyone else was so brilliant.
The reality is, many parents don't have those basic skills. And many more don't have the skills to teach that knowledge. Does that make them bad people? Does it matter? Should their kids be taken away from them for not (or not being able to) teach a 5 year old long multiplication (???)? I would say not. They should be giving a chance to learn basic skills needed in society even if their parents are incompetent, lazy, idiots, or god forbid, can't code. Otherwise, they will be out on the streets when they are older begging for change, selling pencils, or sticking a knife in your kidney and grabbing your wallet.
Its not natural or obvious how to use the three seashells. School is there to teach that.