Many carriers prefer G.fast in buildings where full fiber is expensive to run. AT&T has been very unclear which of their 12M+ planned homes would get fiber to the basement/G.fast and which would get fiber all the way. They've brought fiber to a million commercial locations and I believe more than 10,000 cell sites. It's relatively inexpensive to extend some of that to residences, well under $1,000/home. (The quotes from Bill Smith are from an excellent Alan Breznick interview. Smith, then CTO of BellSouth, led the recovery after Katrina. He's always worth listening to.)
By late 2014, competitors saw AT&T begin a massive "fiber" build in apartment buildings, complementary to their commercial fiber. AT&T engineers played a major role in defining G.fast. The standard was written to the needs of AT&T and British Telecom.