i assume you are referring to backbone providers wanting to charge deep pocket sites like google for access to their sites?
its all about money. the backbone providers see the traffic and google IPO as an opportunity. they basically figure if google is worth 42 billion dollars (whatever it is), then they should try to blackmail them into paying some $ to the backbones for access.
my opinion is that it is driven by a perception of free money, like sueing tobacco companies , that kind of mentallity