I have no idea. The other side is , sonic can make money at $70 with normal rollout costs, why is Google gouging the KC-ites for $70 and hosing them on the normal "cost of business" RoW/power/inspection/franchise/etc. expenses?
Based on every FTTH proposal I've ever seen a $70, zero install is a non starter UNLESS someone give you the money for 30 years for free or you can get and keep a very high take rate with 10years plus VERY low interest rates. If Dane Jasper wants to open his books/share his secrets, I'm sure lots would be interested (it would be nice for Google to share some info too, but I'm not holding my breath for either one.)
Google shopped around for a market that would make its deployment road easiest. Sonic.net picked areas where it was already established. Both are ways to guarantee X amount of customer participation/cost spreading.