It's a gradient. People with existing identity docs are frictionless, state IDs, driver's licenses, passports. Heck, ID.me and Stripe Identity can proof these folks remotely. People without those docs still have birth certificates and other legacy identity docs. You use trust anchors and identity to proof them into new identity systems. The latter requires a solid and robust ground game, similar to USPS or the US census, to ensure extremely high rates of coverage to prevent disenfranchisement or a digital divide.
(a component of my work is digital identity/IAM)