This is for the UK. Dunno about elsewhere. Dunno about competitors in the UK.
I remember having this idea in the late 90s (while in London, moving around frequently) and did a net search and found that there was a provider of such a service even back then. Do not know if it the same crowd since way back then.
Of course all of this automated centralization will result in security holes, so that'll suck, especially if the federal government's fallback is the woefully insecure social security number.