The government is controlling how children spend their time. In the U.S., the government mandates a lot about how children spend their time. They need to go to school and they aren’t allowed to buy alcohol or tobacco. Children under 16 aren’t allowed to spend any time driving an automobile, etc.
To justify any arbitrary regulation imposed on children.
No child owns his own life or decision making. Typically parents make most decisions, the government makes some others e.g. mandatory schooling, setting standards that parents most abide by if they don't want their children taken away from them (sufficient food and shelter etc.).