Ah, government interference in the market. Gotta love rent seekers who get the government to do their bidding. In this case it's the major carriers who have twisted the arms of the bureaucrats and got them to do their bidding. If you've got a phone you want unlocked you'd best get to it.
http://mashable.com/2013/01/23/unlocking-cellphones-illegal/
http://mashable.com/2013/01/23/unlocking-cellphones-illegal/