I'm surprised Comcast hasnt gone after Netflix already.
They have, and been caught. The whole Net Neutrality thing was over this very concept. The example was that the location of the Peering nodes were deliberately not upgraded an thus Netflix traffic was impacted. Netflix went so far as to say that they would pay for all the equipment needed at all of the peering locations, and even install CDN points INSIDE Comcast's network to help prevent the congestion problems for Comcast's Netflix customers. Comcast said no thanks.
Comcast has a vested interest in both Broadcast and Cable TV, and Netflix has a direct impact on both. Comcast is not going to help Netflix even if Netflix does all the work.
However, since this is all being done on the Network side, it is hidden (obfuscated) to the customer. All they know is Netflix streaming "sucks" a lot of the time, while Comcast streaming almost never does. The customer doesn't see it as a Comcast problem, they see it as a Netflix Problem.