I believe Netflix's contracts are set up where they pay a one-time annual rate licensing fee, rather than, say, a per-view fee. Most of the time this may work in favor of the ones supplying the films, since most of their individual offerings put up on Netflix probably aren't viewed that much. But other things can interfere with the contract...like with the Starz contract, individual companies could try to pull their movies out of the deal/off of Netflix, like Sony Pictures did for a while when they did their own re-negotiations with Starz.
The Starz contract was, imo, what helped Netflix a lot early on. It was for 30million a year. But they now want something more like 300million a year, along with other specific conditions, and the contract fell through.
Quote from http://www.usatoday.com/tech/news/story/2011-09-01/Starz-quits-talks-to-renew-Netflix-streaming-deal/50224638/1 about one of the things Starz wanted:
"
Instead of making their content available to any Netflix subscriber paying just $8 per month, Starz executives wanted viewership limited to people paying at least $16 per month for a package that bundles DVD rentals with Internet video."
From the public response to Netflix trying to raise/alter their pricing tiers etc, I'd say most customers aren't willing to pay more for more...at least not on the internet. I would be, but....oh well.

Yeah, I was glued to my TV for a few seasons, with that show. Good stuff. Glad you're enjoying it!