Typically, licensing fees are negotiated for a few seasons at a time. It's a flat rate per season, so whatever production costs are incurred, they're paid for by the studio — not Netflix. If something goes over budget, Netflix has already paid to use it. Likewise, if a show is immensely successful (like, say Orange Is the New Black), Netflix doesn't have to worry about paying more for that, either.

So by keeping viewership numbers private, Netflix actually has an edge in licensing negotiations between studios. Because if a studio doesn't know how popular a series is, it's harder to push for more money.