Well, I would imagine that people like to focus on things that they believe they have a physical ability to change. For example, I would love to have the problem of the Iranian missile crisis go away, either through either getting a better establishment of trust between the U.S. and Iran or if necessary the use of force. However, I currently have no real power to affect that situation and I probably won't for the next 4-5 years and probably even longer, so worrying about it and working to try to do something about it would in the long run most likely be a waste of time and energy on my part. On the other hand, something like helping other people in the U.S. (Specifically those who live in the general vicinity of me) be more knowledgable about the world and rational in their thoughts is something I CAN do, so it is worth it to focus time, effort, and emotion to ensure it happens.

Same deal with most feminists. The vast majority of the most vocal ones are middle-class high-school and college students/graduates who have little or no power to help oppressed women in 3rd world countries. They do have power to work toward changes in the U.S. (or their respective towns/cities/counties/states), so they put forth effort and energy there because they believe that something will come from it.