Part of the issue is that Verizon is a last-mile network, and does not sell symmetric bandwidth to its subscribers. So, the typical agreement between providers - where they each send about the same amount of traffic to each other and upgrade the interconnects to handle that traffic - will not work between Verizon and Level 3. Verizon (and the vast majority of other last-mile providers, including Comcast) will NEVER have a balanced interconnection with Level 3, because the home subscribers can all download far faster than they can upload.
Really, it's Verizon's customers who are causing all this bandwidth usage, so it should be Verizon ensuring that their interconnects can handle the requested bandwidth. If anything, Verizon (and Comcast) should be paying Level 3 for additional download capacity... but we all know that is never going to happen.
One picture is worth 128K words.