So a key part of the "cost saving" is that AT&T gave them cheap access to poles. Doesn't that mean they are relying on one of the very competitors they will displace to collaborate with them in this? Seems to me that either AT&T was forced to do this by competition laws OR they indulged this little experiment as a one-off but the chance of them or any other telco letting Google scale this up to the point where it matters is zero.
I believe most of the poles are not AT&T's, but rather owned by the county and it's Board of public utilities. The combined power and communication poles have a standard fee for attachment. Google got a special deal to use the power area of the pole for free as part of their enticement. Labor cost is higher for the power area of the pole.
The AT&T deal is probably for just the odd pole where the communications approaches a building from a different path.
Does anybody know which one it is?