Netflix really hates data caps. In their eyes, any barriers that restrict their customers from streaming loads of TV shows and movies should be removed, which is why the company has asked the Federal Communications Commission to ban data caps in the United States.
According to Netflix, data caps on wired networks are particularly bad, as they "do not appear to serve a legitimate purpose." In a letter from Netflix to the FCC, the company also says that data caps do little to prevent network congestion, and instead "may unreasonably limit Internet television viewing".
Netflix does have a point: charging users by the gigabyte is an artificial limitation implemented by ISPs like Comcast to get more money from consumers. In telecommunications networks like wired broadband, the actual limited resource is bandwidth, not data, which in many circumstances is already restricted based on the plan or tier a customer purchases.
The letter from Netflix specifically targets Section 706 of the Telecommunications Act, which they claim allows the FCC to rule that "data caps on fixed-line networks and low data caps on mobile networks" are unreasonable. This could lead the FCC to ban data caps altogether, or at least pressure ISPs to raise any caps to a more reasonable level.
As for mobile networks, Netflix is worried that low data caps are just as unreasonable for everyday media consumers. Netflix seems to understand that some data limits are required to prevent users from overloading mobile networks, however the company does not like data caps that are too low, as they lead to less streaming over mobile connections.
Netflix didn't clarify exactly what they think is a reasonable data cap for mobile networks, but they hope the FCC will convince ISPs to raise mobile caps as well.