I don't think that is entirely true. If you have an active AT&T account in good standing you can unlock 5 devices a year as long as the contract tied to the device is fulfilled. I've unlocked my brother-in-law's iPhone with my AT&T account without a problem. The social security number and phone number are just to access your particular account. In addition, thats why it gives you the option for being a current or former AT&T customer. So those that were former and no longer have the service but completed the contract then have to use their SSN and phone number to unlock it, but those that are still active can just unlock once the contract is up.
I recently tried unlocking an out of contract 5S (the person paid the ETF.) Entered my own info, and AT&T denied the unlock request. Called into customer service, they wanted the owner's info, then a few days later the unlock was approved. This was my most recent experience, about a couple of weeks ago. However, this has been the same for every iPhone I've tried unlocking, which is a total of 5. From 4's to the 5S. AT&T I know for a fact has been cracking down on unlocks, especially of iPhones.
I'm not say some reps won't unlock it, but in general, the original owner's info is needed to unlock an iPhone.
As for the person who mentioned their Note, as was stated to you, iPhone unlocks are the hardest to get right now. The newer the iPhone, the harder it is to get unlocked.