I think that the only reliable way to verify that a user is a real person would be to coordinate this work with government. Kazakhstan allows for each citizen to get a signed digital certificate to use it for government websites, but it's possible to use it everywhere, it's a plain X.509 RSA certificate signed by a special certificate authority. I'm aware that there are many countries doing exactly the same thing. So many people already have certificates to verify their identity and they have an incentive to keep those certificates secure. It should be possible to build an analog of "realpeople.io" using those certificates (or directly use certificates for authentication).