That would be news to Apple and Apple Legal, who specifically says Apple Warranty for iPhone, may be limited to the country of purchase.
Contained in the official Apple iOS Warranty is the following:
IMPORTANT RESTRICTION FOR iPHONE, iPAD, APPLE TV and HOMEPOD SERVICE.
Apple may restrict warranty service for iPhone, iPad, Apple TV and HomePod to the country where Apple or its Authorized Distributors originally sold the device.
"May" almost 100% means if a phone is purchased in the US, then used in another country, Apple will require the phone to be returned (not by mail) to the country of purchase for warranty support.
Legal - iOS Warranty Document Us - Apple
I'm not sure where you got your law degree, but Apple is pretty good about being up front and specific with warranty claimes.