Earlier quoted context omitted.
This comment does raise a serious concern. The primary reason why cell phone numbers are bad for 2FA is sim swapping, which can only occur because there is a customer support rep who can fall for it. Email is largely immune to that right now because customer support generally cannot let you into an account you locked yourself out of. This isn't to say that this is an unsolvable problem, it's not, but it's definitely…
I'd like to see the Post Office (in the US) get involved. Post offices are geographically ubiquitous, already deal with identity verification, and already have to maintain the trustworthiness of their workforce. I'd like to see a system where (a) an account [whether GMail, Facebook, Schwab or Bob's Online Pet Food Mart] can be tied to a real-world identity and (b) when you lose access, you can go to the local post of…
This sort of solution (and your post office idea) can be, but they don't satisfy the last resort customer service role, for people who haven't set these kinds of recovery options up.