>The real issue is what happens after you've completed the 18 or 24 month contract. The carrier recouped their subsidy on the phone and has profited from your contract. But you can't use your phone (which you have more than paid for) on any other network.

I'm not so sure this is true. Carriers will allow you to unlock your phone once your contract is up, and according to this DMCA law, it is legal to unlock your phone if your carrier allows you to do so.