Is anybody really surprised by this? I mean, Google has some of the best and brightest engineers working for them, a substantial budget, a purpose other than profitable retail of their service, and a tiny town outside of major populations to work with. I would be hard pressed to find a reason why they wouldn't be faster than anyone else out there. Shoot, I bet you could find similarly sized cities were Verizon/Comcast/Charter handily beat Google Fiber. Don't get me wrong, I love that they are doing this, but everything breaks at scale
EDIT: Misread the part about it being Kansas City vs. a city in Kansas. I feel my point about scale still stands, as Kansas City in total (Missouri and Kansas) is in the 6-700,000 person range, and is still a fraction of total user base of the other ISPs mentioned