When I start an interaction, I have a task in mind. I've already done a rough calculation about the value of the outcome and the cost of achieving that outcome. I assume a sort of contract with the other party: I'll do this and you will arrange for me to benefit as I expect. Yet few interfaces acknowledge this contract.
The Verizon example is an easy one where an expected simple purchase consumed hours and ambiguities still remain. But I mean something more general. When I set up a channel on iTunes radio, as a paid service, just what is the deal? Am I agreeing to be marketed certain songs that are inserted into the stream? Who am I rewarding? Am I contributing to the sort of change I believe is good? How could I possibly know; the interaction process is opaque even through it is painless and brief.
Suppose I choose to watch a movie in a theater. Some of the deal is obvious: ads, germs and snack extortion. But much of it is occluded. I would like to know what I am doing when I do it. iPad apps with in-app purchase surprises after you've invested some part of yourself are another example.
I cannot trust even the simple action of typing a URL these days.
We need to know what we are doing before we engage, and if that adjusts along the way we need to know how.