Can you not use the iphone is all of those area's what's the point in that? why would it be using gophone's coverage and not the full at&t network?
The full coverage
shown here as default, includes roaming agreements. So you can
use the phone everywhere you see, but to
own one, you have to live in ATT home areas.
When you click GoPhone under Coverage Type, then you're seeing where ATT has its own native coverage.
ATT does not have rural coverage in Montana, the Dakotas, large parts of Colorado, New Mexico, Oklahoma, Kansas, New Hampshire, Maine, Utah, Oregon, etc... altogether about 1/3 of the states.
More info here. (Note that Vermont just now got coverage through a merger.)
What that means, is that you'd be roaming more than 40% (I believe that's one form of their limit) if you lived in those areas and owned an iPhone. Which means ATT would drop your contract (if you managed to get one at all by lying about where you lived).
Much of those blank areas are covered by rural GSM and CDMA carriers. The Rural Carriers Association has
therefore petitioned the FCC to force the Big Guys (Verizon, ATT, Sprint, etc) to let them sell their exclusive phones in places not natively covered.... so that everyone in the country has a chance to own the best smartphones.