From what I've seen locked phones only exist in America.

Everywhere else in the world (I've been to), buying a phone on a plan means you have to pay for that plan until it expires but you can walk out of the shop with your discount phone and buy and use any prepaid card or plan with another carrier unrestricted.

That means, if you have a phone in the family without a plan, you can buy your new phone and stick its sim card in the phone without a plan and buy yourself any plan you want with whoever you want for the new phone.

Travel overseas and you are unrestricted to using any pre-paid card.

Obviously, this is the way it should be world wide.

The only thing that's important is that the supplier gets the money for the period they require for the discout on the phone. All other factors should be irrelevant.

I can only assume that the method used in America is done because American phone companies don't trust Americans. That's just sad!!!