What you're missing here is that Google has built its own network with large global reach using dark fiber. Almost everybody will peer with a party like Google

What you're missing here is that Google has built its own network with large global reach using dark fiber. Almost everybody will peer with a party like Google if they pop up at the local exchange. By doing this Google can skip most of the usual transit bandwidth tax, which is where most of the money traditionally goes to if you're sending massive amounts of data to end-users.