Zero-rated data is just one more pebble on the slippery slope that US carriers seem to be standing on in regards to net neutrality. The practice of zero-rating, or allowing customers access to certain content without using their data allotment, is not against net neutrality per se, since net neutrality rules apply to favoring some data content over other content in a way that discourages users from consuming other content. The link isn't hard to see, however. The proposed deal between AT&T and Time Warner, an absolutely massive $85.4 billion affair, would join one of the biggest media empires in the United States with one of the biggest purveyors of data connections, and AT&T has announced that they will be zero-rating the content they get access to as a result of the deal.
One of the most pertinent authorities on the matter, the Federal Communications Commission, has more than a few reasons to oppose this deal, and zero-rating is one of them. Some in the organization are calling AT&T's current plan with their upcoming DIRECTV Now service an "example of improper zero-rating", and this deal would be more of the same. Essentially, while customers are not actively discouraged from viewing other content, a wealth of content being available and zero-rating all of it would push consumers toward that offering, which could run afoul of net neutrality. Since other carriers have picked up on this habit, with T-Mobile's Binge On and Verizon's go90 making waves, this seems to be the new norm in the wireless industry, and while not everybody is a fan of it, current net neutrality rules don't cover it explicitly.
Essentially, the current state of affairs allows carriers to use strategic zero-rating to box out the competition and influence customers' choice of carriers all they want. According to FCC chairman Tom Wheeler, this is because the situation is not "one-size-fits-all" enough to warrant sweeping legislation. While this does mean that carriers can run amok until told otherwise, Wheeler stated that the FCC will be keeping a close eye on the practice and how it affects the market, choices, and experience for wireless consumers.