> Practically, I am not sure about the feasibility.

Last week I logged into my e-gov website by confirming a push notification on my authenticator app that's tied to my e-ID card to download my birth certificate. No copy pasting needed. Random websites now even support logging in without passwords by using your smartphone passkeys.

I am sure they can make it work for a simple yes/no (over 18) challenge-request scenario.

> Plus, not everybody has a smartphone. Not everyone accepts Android or iOS at their current implementations. Do those people remain without access to the www?

We are talking about adult content. The alternative is having that content banned. Many democratic countries have already done that, like South Korea. I don't prefer this scenario.

The bigger alternative is the status quo: A big button saying "I am at least 18 years old" and some web-filtering technologies that parent could use but probably don't. Nobody's dying over this, so I'd be wary of arguments along the lines of "we have do do something anyway".

the alternative is to force parents to do their jobs. We don't need the government protecting us from everything. What do they want to protect us from next? Car accidents (stop allowing private car ownership). Being fat (monthly weigh ins with fines if you don't get down to your target weight?). Where does it stop?