You can block the entire internet and whitelist specific domains. There's multiple ways of doing this, from router parental controls, specific OS tools in iOS/Android, Windows, as well as apps specific to it, and all it takes is for a parent to care enough to make a simple Google or Youtube search and learn if they don't know, and don't even know to know that they should care in the first place.

The failure here is two-sided.

One and the most glaring are the parents who let devices raise their children, this hasn't changed since before home computers were a thing.

Secondly it's a failure of the state for not educating both adults and teenagers on best practices when using online platforms to be safe. If they're interested enough in policing people's web habits, they can spend time and resources on educating the masses. The best time to start doing it was 20 years ago, the second best is now and it could take a decade plus for it to have a meaningful impact.

Also this is important. The UK, like it or not, is a nanny state. They like to use child safety as an excuse to police adult habits, and more important their speech. There's quite a few times they've admitted to this plainly without any ambiguity.

"The Online Safety Act 2023 (the Act) is a new set of laws that protects children and adults online"

https://www.gov.uk/government/publications/online-safety-act...

There's also examples of them being asked directly in interviews and they admit to wanting to police adults speech and content they consume online.

Australia is in a similar predicament and honestly most of the world is rolling towards this, just not as fast as the UK.

The UK unfortunately has incarcerated people for simply lifting cardboard signs saying Free Palestine. They've jailed people for innocuous social media posts on Facebook and other platforms.

I'm not proud of the USA for a lot of reasons, especially lately, but one thing that any and all Americans should be proud of is their Freedom of Speech protected by the First Amendment, it's the most American thing and one of the best aspects of America that other countries should aspire to, and I hope that the jabs Freedom of Speech has taken over the past decade doesn't make it crumble away.