Sprint and T-Mobile have significantly worse networks and access to spectrum.
Does not help that AT&T and Verizon are also huge stakeholders in the wired telecom oligopoly. They are overflowing in cash to crush competition.
Google margins are way higher and Verizon employees more call center reps then all of Google in total.
From my understanding Google fiber is basically cheap dark fiber they got with some great regulatory concessions.
My view of it is Google spends enough just to prompt others to take actions (see their involvement in specturm bidding). Though my post might come off as judgemental, I'm not judging Google - that's merely good business for them to do. Wireless companies themselves are hardly examples of efficiency.
Their involvement with spectrum bidding got them open access rights for only a few million.
Maybe I'm missing something obvious here though..