If being forgery-resistant is the argument for paper docs, a passport that identifies me using strong cryptography is just as forgery-resistant (likely more so). And we could do a cryptographic verification without a persistent internet connection. (Or can’t we?)
Even when there's no connection, no electricity, you get some modest layer of security out of "it's hard to manufacture a convincing fake passport if you don't have large-scale resources behind you."
What happens then with app-only passports? Do we close the border crossing entirely until the network is back up? Or do we rely on showing a QR code or NFC handshake that can't be properly verified? I'd think creating a fake passport app that reached those hurdles would probably be easier than getting access to specialized papers and printing technology.
A passport with strong cryptography would be forgery-resistant, however it is dependent on some form of PKI to distribute the public keys to every customs/border inspection point across the world, for every passport-issuing nation.
