Don't just look at the data caps if you want to understand what Comcast is doing.
The company introduced a streaming video service in Chicago (where data caps have not yet been implemented) for INTERNET ONLY customers. It will not count against the data cap because Comcast calls it a cable TV service over internet. So, Comcast institutes data caps that will mainly impact "cord cutters" that only watch videos over streaming services, then offers it's own steaming service that is exempt from the data cap...this is a play to either make customers pay Comcast more to get streaming video through them, or pay Comcast extra in the form of "excessive" data use so they get additional revenue anyway.
It's such an obvious ploy that I am insulted Comcast thinks that we are too stupid to realize what they are doing. On the other hand, perhaps they just don't care. As long as they have politicians fighting at the local, state and federal level to protect their anti-consumer practices against competition and regulation, they really don't have any motivation to make customers happy.