This is another "for all practical purposes thing".

Let's say the typical US consumer has two choices:

1) an unlocked phone for $600 paid upfront + service plan;

2) locked phone for "free" but actually costs them $800, spread out over a contract

By and large option 2 will be selected. That's just the way it works here. And the really funny thing is, many people opting for choice #2 will subsequently seek to unlock their phone after they get it.

The point is that cost is *almost* a moot point of any discussion involving US cell phones and users. For the most part they're very programmed by the status quo. It all comes down to "what can it do?"