The government once asked Apple to unlock a phone that wasn't even password-protected
Here's one request that must have infuriated Apple: a government official once asked Apple to unlock a phone that didn't even have its passcode turned on.
From the New York Times:
Apple's annoyance with the growing number of legitimate government requests was deeply influential to Cook's thoughts on security and privacy, which have culminated in a public challenge to the FBI in its request to help hack a terrorist's smartphone.
Filling these requests was tedious for Apple. Lawyers had to vet each request individually. And when a request was valid, Apple needed to dedicate spy-level security and significant resources.
According to The Daily Beast, Apple has unlocked at least 70 devices for authorities since 2008. And as Cook has mentioned, foreign governments can make the same requests as U.S. law enforcement authorities.
The increasing wave of government requests facing Apple was a major factor in shifting Cook's views to a place where he would decide to publicly challenge an FBI court order.
To a lesser extent, the annoying and expensive security procedures around lawful requests explain why Apple is seeking to build devices that encrypt personal data like contacts, messages, and photos in a way that Apple can't unlock them, even if it is compelled by a government agency.
The entire profile at the New York Times is worth a read.