Earlier quoted context omitted.
IMO slippery slope is a fallacy when the small step only supports the big step symbolically, shifting the “Overton Window”. It’s true that the Overton Window has some effect, but we shouldn’t avoid taking a step towards the middle just because it’s also a step towards the opposite bad side, if the middle is good. Wrt. privacy, the real issue is that the small step helps the big step not just symbolically. ID-based ag…
IMO the problem isn't ID-based age verification specifically, it's that such verification is usually impelemnted in a way where the service in question gets a lot more data than they need, with no real control over how that data is kept and processed. It would absolutely be possible to implement that stuff in a fully privacy-preserving way, with nothing but basic cryptography, and the government could absolutely enfo…
What are some implementation(s)?
Different implementations vary in effectiveness. Anyone can give a minor access to their device, or a minor can steal their device. So in order to prevent access then, you'd need something like constant face monitoring (via a local model, possible to do anonymously, but expensive and fallible), or legal threats (impossible to do anonymously, because you must track the adult who gave their kid access; and many people are dumb with technology even when it matters, so you either have to fine or jail many people or selectively enforce).
The easiest implementation I can think, which I'd recommend, is to make locked-down kid devices, require ID or even just a credit card (18+) to purchase a normal device, put the burden on adults to not share their device with kids, and only police merchants (for selling normal devices without ID) and websites (for serving adult content without blocking kid devices). Like what we do with alcohol, except not even trying to police people for sharing, because it would be ineffective and messy. Like alcohol, many kids will get access anyways, although less than now.
I like this approach because, IMO importantly, kids who don't try to see adult content will be far less likely to, and parents who try to restrict their kids from adult content will be far more successful. I don't think you can stop determined kids with neglectful parents without drawbacks.