This is actually a level headed way to deal with it. Provide a way for the device to inform the website / app of their age status (it can be bucketed for increased privacy/compatibility with existing rating systems). Then legislate that it is on the website to inform the device of the type of content being served. Then the device/browser can be responsible for implementing the privacy controls (page blocking, notifications, overrides, etc.), and the parents are responsible for ensuring their children's devices are configured with their ages.