That's the clearest explanation of the problem that I've read so far.

I've always known that there was something inherently wrong with charging by traffic, but I could never put my finger on what it was. A clear explanation, such as you've just provided to me, on exactly how the internet works and is billed at higher levels makes things obvious.

Traffic is a problem, but only insofar as it contributes to saturation of the overall available bandwidth of the existing infrastructure. Calling the problem "traffic" is just a convenient scapegoat for other concerns that can't be directly billed as easily, even if traffic isn't the real problem.

Thanks. I'm always impressed by the quality of discourse on Hacker News.