How do the apps that scan the NFC chip in a passport to ZK proof prevent fraud?

What type of fraud are you curious about?

Rated 💯 by multiple networks. Fluent in /unglish. Unbothered by /whatday of the week it is.

Allegedly a designer.

Input > ZK proof that I'm from the US based on a passport

Just fake the input?

No, I'm saying what if proving you live in country X is valuable.

Wouldn't you have people creating fake NFC chips with seemingly real passport data from country X?

What do you mean fake the input, though? You need to hold a passport. Are you asking "what if somebody else gets access to my private key"?