Honest question: what does T-Mobile think data actually is?

Here are two lines from T-Mobile’s latest "Uncarrier" missive, in which the company proclaims that it has "listened to customers" and is changing its new T-Mobile One plans less than two weeks after announcing them.
The first line:Everyone gets unlimited talk, unlimited text and unlimited high-speed 4G LTE smartphone data on the fastest LTE network in America.The second line:With T-Mobile ONE, even video is unlimited at standard definition so you can stream all you want.At this p