Re: New AppleCare Support Tier: Go away complainy-pants
They're not. AFAIK nothing is locked any more. My current phone was not locked, ever. My previous phone was locked, and after a year Sprint unlocked it for the low, low price of asking for it to be unlocked.
Not true universally. I did a brief stint as tech support with T-Mob USA. Their handsets were always locked. They would unlock on request provided the device was paid for in full. Outstanding credit on it - no dice.
I would assume most other carriers are at least as strict, T-Mob tended to be kinder to the customer than average in that sort of thing at least.