Maybe this makes more sense when I put it into my work. At University, we believe that Christianity is about more than just make a decision and profession, it is about a lifelong journey of discipleship. We want people who join the church to engage in this journey. However, we know historically that most people will choose to remain on the sidelines, attending church semi-regularly. We know that some will eventually lose interest and drop out. Some of the people who remain on the sidelines or even drop out make an intentional decision. Most however are, at first, truly committed to growing in their faith. But they get busy and distracted and fall off track. We know that being in the pathway, being in Bible study, learning about their faith is good for them. They know that it is good for them. They need a "nudge" that will help them to stick to what they want to do and what is good for them. As a discipleship staff, we struggle with how to do that without being coercive or manipulative. It is truly each person's choice but we want to do what we can to help them make smart choices.
You might enjoy this book even if you are not trying to make systems that help make disciples. If you like the genre of pop behavioral economics: books like Freakonomics, The Tipping Point, etc. or are into looking at the forces that shape modern public policy you might enjoy the read, especially if you like economist humor.