This is all "how can we optimise this interaction even more, and even more, and even more?" over time. There is always one more thing you can do to further manipulate sales out of people that otherwise would not occur. The simplest interactions will continue to be optimised further and further, in excruciating detail and thought about how the psychology plays out.
deleted by creator
Yep that's precisely what's going on.
This is all "how can we optimise this interaction even more, and even more, and even more?" over time. There is always one more thing you can do to further manipulate sales out of people that otherwise would not occur. The simplest interactions will continue to be optimised further and further, in excruciating detail and thought about how the psychology plays out.