The majority of senior volunteers here know that, in most countries, Apple limits warranty coverage for iPhones and iPads to the countries in which the device was purchased:
Your Hardware Warranty
Scroll down to the section titled "IMPORTANT RESTRICTION FOR iPHONE AND iPAD SERVICE." The policy is published so it is not a secret.
We are end users like you, not Apple employees or agents, and have no idea why Apple policies exist unless Apple has published a reason. That almost never happens.
In fact, discussing Apple policies in theses forums is not permitted under the Terms of Use we all agreed to when we signed up to participate here. It is Apple's playground and they make the rules. These forums are intended for user-to-user technical support, not policy, financial, or human resources questions.