@BeAware I have no idea why Elk refuses to mention you properly. Might be a bug.
Relying on 3rd party platforms is far from ideal and like you mentioned unrealistic as it would require API access which would be easily blocked.
Realistically, I can only think of one idiot-proof verification system. Credit card, but that opens up instances to storing payment and identitity data or outsourcing it to a 3rd party service. Anything else would be user based and require at least some input from them.