But the ISPs don't have to be big cbrother at all. All they have to do is react to a formal complaint. Then react accordingly. I am by no means endorsing a complete "inspect all traffic" approach. But if ISPs were just more responsable about traffic originating on their networks there would be less, local at least, spam. This means better network reliability and response. That means happier clients, who would probably pay a premium for this convinience.
The legal side is actually cut and dry. The T&C state the rules which as a client of an ISP you accept. Break the rules you get fined or lose your "license". Highways have these rules why shouldn't the info super highway?
I would be very interested to hear a response from ISPA or somebody at the bigger ISPs on this.