Imagine you have a nice phone your bought and you've finished up the phone contract, and then you move. Your old phone company has terrible reception (or doesn'

Imagine you have a nice phone your bought and you've finished up the phone contract, and then you move. Your old phone company has terrible reception (or doesn't operate) where you've just moved. So you'll need to change phone companies. But your phone is locked. You are forced to buy a new phone, even if your old phone works fine. If you were legally allowed unlock it, then you wouldn't need to buy a new phone.