There was an opinion that US carriers lock carriers, instead of regions. But dphm00 seems to be refuting this.
It could be too that the Verizon edition is more open than the AT&T one and possibly also Tmobile. All of Verizon's 4G phones IIRC are factory sim unlocked as part of the condition for their use of the 700 band LTE spectrum.
I thought it was funny when a few AT&T customers were recommending that people buy the VZW Iphone if they were going to pay full price anyway. It actually makes sense when you consider that it can function uninhibited on all the U.S. Networks except Sprint.
If they ever had a Verizon Android phone with the same band support, I might buy it. As someone said, I'm sure Verizon cries tears of rage, knowing that the Iphone 5s can be taken directly to Tmobile and AT&T, but they have no choice because of their deal to get the 700 spectrum.
I just wish Verizon would get the next Nexus, but maybe the VZW Note 4 will support the other bands.