The simple part is that it happens the same way whether it is one person or a thousand. It gets more complex when you put an organization into the mix. One way that I like to think of this is that people are always committed. They are either committed to a desired state, or to a current state. Most of the people with whom I have worked have been very responsible in doing what they saw as "their job", and delivering to the best of their ability. This is where leaders often miss. When we describe a new desired state for the organization, we only create a glimmer of how that will work, and leave all the details to the organization to work out. In the meantime the work world people experience does not change significantly, and the result is that there is no overall change in the work output.
Organizations are designed to create a focus on a few things. This is how we build stability and predictability into a group of people. However, most leaders are not organization designers, and don't understand how this is created. More importantly, they don't know how organizations are designed to dampen forces for change. That creates a tendency to miss the actions they need to take to change the focus of an organization. One rule that I learned early in my career is that if you want to know what an organization is designed to do, look at what it delivers. All organizations are designed perfectly to do exactly what they are doing. Simple and straightforward. If you want it to do something different, you have to change the design.
Now, one more clarification. This is the organization design, not the org chart. Over the years, organization reporting structures have been confused with the organization design. They are not the same, and in fact, need to jointly optimized to deliver the best results. This is a key skill of our new generation of transformational leaders. They understand the basic mechanics of creating sustainable change inside of organizations. You only need to know a few things to do this, and learn subtlety different ways of engaging people. Once you see it, you'll wonder why you hadn't done it all along. You can learn more about this in The Ten Tasks of Change (Jossey/Bass:Pfeiffer, 2001) or Inspirational Presence (Morgan James, 2009).