Same here. I signed up late last year and they used the same kind of credit bureau-based system that social security uses to verify your identity by asking questions about previous addresses, current mortgage or car loans, etc.

Maybe it would be good to also add in a postcard check where they send you a code to verify you have access to mail for the address anyway. Sure, a thief could too, but in that case there isn't much of an extra risk to informed delivery since you'd be compromised already.