The more apt analogy would be if UPS decided to make Amazon packages ship super slow unless Amazon payed extra fees to "upgrade" the shipping speed back to average.
You could make the case that Comcast should have upgraded their peering with Cogent. That's the case in almost all of these disputes. But Netflix blinked first.
If you want to make useless shipping analogies, it's like Amazon ships using ABC to a rough wilderness. ABC uses simple cars that don't handle the terrain so they contract the local government to deliver packages in that area. You could say it's the local government's responsibility to fix the roads, or ABC's responsibility or anyone but Amazon's. Good luck.
Really, the point of the Internet is that you can communicate with other Internet users without having to worry about what ISP or network they are connected to or what arrangements govern that connection.
I think it's ridiculous and self-serving for internet companies to complain about this. Getting bits to customers is a critical part of any online business. You can either do it yourself, or pay someone to do it. Does Amazon complain that UPS charges them to deliver packages to customers?