Except it (a) isn't, and (b) even if it theoretically were, the model of having to follow the rules of every ISP on the planet to fall under their respective zero-rating plan, or even just the overhead of coordinating with them doesn't scale, and thus is inherently only an option for large companies. Being accessible globally via IP is a matter of renting a small virtual server for a few bucks a month. Being zero-rated by thousands of ISPs is a major undertaking.
And also, obviously, that ideal is completely unrealistic: Either the ISP gets to look into the video stream to verify that it is indeed video, which would be awful, or what you in effect end up with is a flat rate for "medium bit rate connections", which would be fine, but absolutely not what any of those ISPs want.
First, the free data is slower than what you get normally. Second, the program is supposedly open for anyone to join.
If BingeOn was the worst impingement on net neutrality, we'd be in a pretty good place.