What is the primary goal of having children attend preschool in japan and most of europe?

The correct answer is to learn social skills

Preschool which is also called nursery school, kindergarten or playschool, is an educational and learning institute for children aged around 2.5 years. While a preschool's main focus is not formal academics, it focuses on play, group activities, painting and socializing opportunities for children. Children at preschools learn social skills when interacting with other children and teachers. For instance, children learn how to wait their turn, how to share and politely request for something.