You require a human to identity proof in real life and bind that to a digital identity with a strong authenticator. Anti fraud detection systems can suspend or ban if evasion attempts are detected. Perfect is not the target, it doesn’t have to be.
See: Login.gov (USPS offline proofing) and other national identity systems.
>You require a human to identity proof in real life and bind that to a digital identity
That's going to be a no from me, dawg. I'm sympathetic to ID checks like if you're buying beer or whatever, but not linking my real life identity to discord or whatever.
There are laws, but in many countries they are not strictly enforced. In Japan, buying beer in the self checkout lane will just give you an “are you over 20?” prompt, no verification: https://news.ycombinator.com/item?id=46227987
I don't know how it works where you live, but in many jurisdictions around the world (including the one I live in), you have to provide ID to prove that you're of drinking age.
Which is by nature transient. There are many more and quite dangerous strings attached to doing this online. You never know if all parties involved in the verification are trustworthy.
See: Login.gov (USPS offline proofing) and other national identity systems.
(digital identity is a component of my work)