Rolling out new infrastructure like this requires an immense amount of coordination and support with the local municipal governments. Between cities of relatively the same size and layout the sunk costs may not vary much, however the ease of obtaining permits, gaining access to main lines, having city hall support, etc. etc. can be worlds apart.

The first Google Fiber campaign seemed to me like it was more or less "Which city government will bend over backwards the most for us?", and I'll bet KC ranked first with Austin close behind. It wouldn't surprise me at all if there were well entrenched interests, especially in SF, that would prevent Google from making an easy entrance there.