Google can probably infer what I had for breakfast from the way I move the cursor. Can't we have ID-less age verification somehow? Sure, it won't be 100% accurate but keeping out 90% of the kids is a win.

They should just do something like have parental controls that can configure the user agent with the user’s age, and require adult websites to not serve underage users.

It wouldn’t deter kids if you want to let them have unsupervised root access to a computer (like I enjoyed when I was 12), but I think it would be fairly effective for a walled garden like an iPhone

We do.

It has a terrible false positive and false negative rate.

So it's not just a matter of it "keeping out 90% of the kids"; it's a matter of it decreeing that due to unknowable factors, and with no ability to appeal to a human, you are 13, and are no longer allowed to access large chunks of the internet.

Already possible! Banks know who you are, so what if there was a safe way to let a site know that you are over 18 — and nothing more than that — through some common API?

This was exactly what the German public transport service Mopla did when I registered an account there. It needed to know my name to be able to sell me the personal Deutschlandticket. To verify my identity their web application forwarded me to list of countries, where I selected the Netherlands, and then my bank from the list there. That forwarded me to my bank's digital environment, with the request to share my name with Mopla (and just that one attribute). I then used my bank's auth system to approve sharing that claim.

Simple, transparent, and at no point did Mopla have to do anything with ID cards or AI or whatever.

I would expect systems like this to become more broadly available in the near future. In the EU for sure.

No, let's not encourage Google and the rest of the ad industry

Google launched ID-less age approximation in July in the US:

https://blog.google/technology/safety-security/age-assurance...