Does it accept a passport from any country? How are they verified? Couldn't counterfeit passports slip through? How do you make sure a passport is used only once? Doesn't this make you a target to a state level attack?
As far as a state level attack, it's possible. A complete solution to Sybil resistance is not simple.
The passport verification service is at https://coinpassport.net if you would like more information.
Stripe Identity seems to very explicitly not be intended to guarantee any form of uniqueness.