Certainly "unlimited plan" doesn't mean "limited to a greater extent than the limited plan". If AT&T had set the bandwidth rate to match that of their normal 5

Certainly "unlimited plan" doesn't mean "limited to a greater extent than the limited plan". If AT&T had set the bandwidth rate to match that of their normal 5GB plan, there would be no problems. In fact, I think that would be seen as expected behavior. What they instead did was punish their long-time customers who were grandfathered into a mistake that AT&T made. I signed up for unlimited data in 2008, after the second iPhone was out, so it's not like the term "Internet" was suddenly redefined and AT&T was in a new paradigm of mobile Internet access. What really happened is that they got greedy and oversubscribed their network, and they decided to punish us for that.