San Francisco, CA
Where is the neutrality violation?
I do no see the violation. Can the subscriber use the application to access the network without a deal in place? I assume that the answer is yes ... but the traffic counts against the users cap. In the case where an app vendor (or web asset for that matter) enters into an agreement, the traffic would still flow ... just not included in your cap.
As long as there is a cap, and this is not the discussion, this business mechanism seems fine.