In Australia we can tightly control our population growth via immigration so we don't need to encourage people to have kids. Kids are essentially considered a lifestyle choice and it's expected that their parents fund that lifestyle.
That said, the role of schools in child care is often overlooked for the less economically measurable benefits of education. Without the child care provided by schools, many parents could not afford to work in developed nations. So dropping the age kids can go to school may be worth while.
Another area of school/childcare/education is the long holidays kids get. Malcolm Gladwell’s book, Outliers discusses the spurious origins of long school vacations.
Note, my wife is a high school science teacher and agrees with Gladwell’s hypothesis that long school holidays disadvantage poorer kids.