Although PGP is widely spread and used since 25 years, after the first, early complaints nobody heard a single hiss from the FBI and its siblings about the IOS-like “problems”. Maybe this is because of the open source license attached to PGP that allows whoever has enough brain, power and money to find ways to crack it. In the past, for instance, the FBI has been able to crack a Truecrypt password belonging to a suspect.
To balance people rights with the needs of the investigation, Apple might just go open source or, at least, disclose to the law enforcement community the IOS source code, thus allowing the “good guys” to develop long-term tools for forensic purposes.
Of course, to Apple, this is an absolutely nonviable option, nevertheless the point stays: should a government be entitled to access each and every source code of critical software?
To put it short, the Apple vs FBI quarrel involves the role of proprietary copyright and has about nothing to do with the “we protect our customer rights” claim.