If there was an actual interest in actual security and privacy at all, we'd have a system something like this:
The government has your data. Like it or not, they do. So the government gives each citizen a token that is anonymous but unique. Like, just a long string of numbers.
If some place on the internet wants to verify your age, you tell it the token and the country it's from. The site then asks the government database if this is a valid token for adult stuff and the government server that knows sends a yes/no back.
At no point does Discord or whoever have my ID or biometrics, but they still know I am of age.
Every incentive to verify age that isn't set up like this or in some other anonymous way is simply an attempt by the service provider to get more information from you and sell it later, or use it to give you more targeted ads, or both. Most likely both. They just get to hide behind the idea that politics is making them do it because politicians that push for this do so on the behest of these same companies, opportunistically pushing the savety of children forward so they can get these laws through.
edit To anyone who sees this after the fact: The worst thing about the internet is that, if you write anything, people will critique not the idea you are trying to convey, but the boring minute details they spot that are maybe not 120% explained in enough detail. They will then hone in on that and call your point wrong, because you didn't write a ten page essay about a topic that should not need even half a page to convey it's idea. Replies like these is why I stick mostly to one-line snark replies. Effort posts are for chumps.