Schools do teach it. It's called "Home Ec" and "Shop Class", but there are only so many hours that they can dedicate to them and you obviously can't cover everything. My home ec class in high school taught basic cooking, sewing and budgeting skills. I still use all three skills today.
They have eliminated the shop class at many high schools and all private and religious based schools. It is something you have to seek out in training your kids now.