Pretty sure it’s already illegal to distribute porn online to kids.

No, not every phone and computer has parental control options.

Which one don’t have one? And even if there are few - it’s not hard to get one with for your kids.

What about the PCs at libraries and schools?

Even in my day and age we had restricted access to things on our school pc - learning to get around it was the only useful thing I learned in those classes. But here the same, there are software solutions to control access on local machines.

What about older siblings? Other students? Friends of the kid?

What about them? They all also have parents or people responsible for them.

It’s completely unrealistic to claim parents should just supervise every media usage.

Because they should not. They should teach children to use media and gradually trust them more and more to make their own decisions. Like with everything else.

You can teach them all you want, unless you completely ignore all privacy rights of your children, you won’t be able to control their media consumption.

And as I said, you should not -you should teach them and then learn to trust them - that’s hard part of being a parent, you don’t have control over your childs life.

Every phone and computer has parental control options that allow for as much control as you feel necessary. And obviously as you kids gets older you have to trust in your upbringing - but that’s also completely on you, to teach your kids to deal with modern media.

Dang, if kids just had some kind of guardians that would be responsible for their media consumption while every media device out there had basic functionality to support such supervision.