No, they're paying for the right to Level 3 access.
> Comcastica is now saying to Level3ton that they're sending far too many trucks for Comcastica's roads,
False.
Comcast has never done this. They say "send all the trucks you can fit on that road".
But all roads have limits.
Netflix says "you need to build another road, I have alot of trucks".
This is literally what happened. The link was 90% saturated. Level 3 themselves admitted this in that blog post the week before last.
I don't mind the metaphors and analogies, if it's to help you understand something that is foreign to you... but that's not a license to twist the issue.
So without the metaphor, Netflix is telling Comcast that their links do not have the capacity to serve the needs of their (Comcast's) customers. This isn't something that Netflix should even need to tell Comcast; Comcast already knows it. In fact, not being able to meet their obligations to their customers was an intentional decision on Comcast's part. They assumed that their customers wouldn't actually use all the bandwidth they are paying for. But with the rise of video streaming in general, and Netflix in particular, Comcast's customers are using more and more of their bought and paid for bandwidth.
That's the issue right there. Comcast intentionally oversold their capacity (or intentionally under-built their infrastructure, whichever way you want to look at it), and it's now coming to bite Comcast in the ass. But instead of admitting that they did this and working to build out their infrastructure, which would cut into their obscene profits, they're trying to blame Netflix instead and demand that Netflix pay. In short, they're trying to double-dip.
It's a simple fact that if Comcast's customers can't reach Netflix (but customers of other ISPs can), then Comcast has sold a false bill of goods to their customers. They haven't sold them "access to all websites that are willing to pay for the privilege of talking to Comcast". They've sold them access to the internet. An internet that includes Netflix.
So no, this is not like some jackass (Netflix) walking up to Comcast's customers and demanding the right to sell crap. Netflix is already paying Level 3 for the right to internet access, and Comcast needs to provide access to Level 3's customers in order to actually provide what it promised to its own customers.
A more apt analogy would be considering ISPs as cities, connected by roads. The roads are the peering agreements. Comcastica is a city where everyone lives. Level3ton is a city with a lot of warehouses and other commercial infrastructure. The residents of Comcastica love ordering products from Netflix, who has warehouses in Level3ton. As such, the roads between Comcast and Level3ton are constantly crowded with big trucks hauling all the ordered goods from Level3ton to Comcastica.
Comcastica is now saying to Level3ton that they're sending far too many trucks for Comcastica's roads, and wants Level3ton to pay for Comcastica to expand their roads.
Level3ton is, of course, only sending the trucks because the residents of Comcastica are demanding them. If Comcastica's roads aren't large enough, it's because they underbuilt their road infrastructure given the number of residents they have.
The only reasonable course of action here is for Comcastica to take all the taxes they collect from their residents and use some of it to build better roads, in order to service all the vehicle traffic that Comcastica's residents are creating. It doesn't matter that the vehicles are coming from Level3ton, it only matters that the vehicles are servicing Comcastica's residents needs.
[1] Presumably Comcast could route traffic through a common peer to both, but they'd have to pay for that privilege, so I'm going to consider that irrelevant at the moment.