The child in that case is not the user (or at least not the owner). The user is the parent who configures the phone as they choose and loans it to the child. It's no different than Apple allowing a business to configure a MacBook as they choose, including tools to monitor its usage, and then offering that computer to one of their employees. The owner of the device gets to choose the privacy settings, not necessarily the end user.
The child in that case is not the user (or at least not the owner). The user is the parent who configures the phone as they choose and loans it to the child. It's no different than Apple allowing a business to configure a MacBook as they choose, including tools to monitor its usage, and then offering that computer to one of their employees. The owner of the device gets to choose the privacy settings, not necessarily the end user.