> In the EU you don’t need to upload your ID anywhere, the service can use the government’s portal for ID verification. In the case of age verification they can get a yes/no response

The issue is that now the government knows what you are doing online, and that should never be allowed to happen.

I grew up when the Internet was truly free, before Facebook even existed. People shared source code, videos, MP3s, games, regardless of "copyright" or "intellectual property." To some extent, it is still possible to do all of this, but these freedoms are being eroded every day by making the Internet less anonymous. The endgame is obviously to force people to pay for things whose "marginal cost" is zero in the language of economists. "Protecting the children" is just a convenient excuse.

> This is opaque to the service

The "service" is irrelevant. I think most people would trust Porno Hub to be discreet about their visits. That's in their business interest. But now they have to tell your government about all the times you're visiting Porno Hub.

And nobody should trust their government.

Also, keep in mind that western governments share with each other. There will come a time when Australians will try to enter USA but they'll get flagged at the border because the AUS government shared that this particular individual visited Porno Hub and a few other age-restricted websites 7,000 times in the last 30 days. Red Flag!

That's a very good technical solution, but socially it can be foiled by an official-looking alert saying "failed to scan card, please do X instead".

And that's assuming the technical solution is deployed everywhere. I'm in the EU with one of those IDs, and I still had to upload photos of my passport and scan my face to open a bank account. The identification process even had its own app that I had to install.