So you want porn on every web site and have kids prove that they're kids by issuing their school card (because they won't have a real id yet) so the porn get hidden for them or so they get entirely banned from the system?
Nobody's ever gonna show an id to get banned from a website.
Do you see porn on every website right now, since we don't have widespread verification yet? The internet was designed for adults from the start, only in recent years we got a significant portion of kids on it.
The thing is that if you are a kid, your device would be bought and signed by your parent, you have no way of refusing to show ID cause device does it automatically. Of course there is a problem that children could use parent's phone but that's also a way to circumvent current age verification propositions.
The idea is just to sign device once for a kid and let them use it without constant worry.
Nobody's ever gonna show an id to get banned from a website.