We are discussing "young people exploring their gender or sexual identity on the internet". This does include pornography, because it's very accessible and not hard to come by if you search for sexual terms. It also includes social media and online games where predators, and again, pornography is present.

> Porn peddlers would probably pinky-promise not to disobey the user-agent and expose the kids to the content (and get them while they're young).

We're talking about a law. If you distribute pornography to someone who sent the header in that request, it would be a violation of the law. But that law doesn't have any ID requirements or privacy problems, unlike the proposed one.

> However, as we have already seen, asking nicely in the HTTP headers doesn't actually work, it may even help porn peddlers better target children.

To begin with, "targeting children" is preposterous. It assumes that they would not only not care but prefer to have children as users than adults, even though children are less likely to have access to money to pay for content/subscriptions and purposely targeting children would get them into trouble even under longstanding existing laws.

On top of that, the header isn't specifying that the user is under 18, it's specifying that the user agent is requesting not to be shown pornography. It's as likely to be set when the user is a 45 year old woman as a 14 year old boy, so using it to distinguish between them wouldn't work anyway.

Your argument is bullshit. There is no content filter on this planet that will prevent children from seeing blocked content. The children that know how to circumvent the protections will circumvent them. The providers of blocked content will figure out a way around them too.

Content filters only affect law abiding users and providers. The hallmark of an effective policy is to make it as easy as possible to comply with it. Setting a header is pretty damn easy to implement and enforce by the government. It also displays trust in law abiding citizen, who will comply with the law, because they know that it serves their best interests, rather than being shoved down their throats against their will.

The alternative will have exactly the same or - far more likely - worse results, because the cost of verifying every user's age is far too high to be implemented by the vast majority of sites on the internet. It's more likely that when law abiding citizens are faced with laws that are impossible to implement that they just throw up their hands up and close up shop or move somewhere else.

In the second scenario their services might still be accessible in the UK and need to be blocked by the UK government, the online safety act achieves essentially nothing in this scenario.