These aren't equivalent though. I can flash my ID to someone to buy cigarettes at my gas station and reasonably believe that no third party is storing my ID. The clerk looks at it (or scans it? I have actually never purchased anything requiring an ID before), and I go about my merry way.
If I go online to consume adult content, I definitely do not want my identity to be associated with my proclivities, and I certainly don't trust any third party to handle my ID with the sensitivity it ought to have.
That may be true, but it doesn't seem to prevent stuff like this from happening.
https://www.eff.org/deeplinks/2024/06/hack-age-verification-...
Sure, fine - we can agree on the hardcore porn. Maybe we can even agree on exposed female nipples?
What about sex education material? What about any content that includes an LGBT person? Because if you think I'm being hyperbolic, read page five of Project 2025.
It's also easy for almost everyone to avoid worrying about the lines by just... not trying to exist right along them. If your photography discussion site just has a "no nudity" rule (or blanket puts nudity into its own adult-only section), then you don't have to worry about whether your photo is tasteful art or porn. These are normal rules anyway because sometimes people want to look at their hobby sites in public or at work and just see bird photos or whatever and not have passersby think they're a gooner, or see a surprise decapitation, etc. Even 4chan moderates their hobby boards and separates which ones allow adult material.
Sites with user generated content already have to have some level of moderation to remove copyrighted or illegal materials (e.g. child porn). So it's not a big difference to say if you want to have user generated content and not be considered an adult site, you need to take down any submitted adult content (or only allow it in adult verified areas or whatever). If HN doesn't allow people to post their amateur smut stories, it could then be unaffected.