Making Friends

It seemed like every year in grade school, a survey we took in school asked "How do you think you are at making friends?" or "Do you think making friends is easy?". I never knew how to respond to that question because I was always satisfied with my current set of friends or that everyone that was in my class was someone I thought I was friends with already or didn't care to be friends with them.
At lunch, a couple friends and I were discussing how simple it was to befriend peers while we were children. Children are usually more open-minded and approachable, whether that be at the playground or around their neighborhood. Adults usually seem to be content with their current affairs; enough to avoid making any effort to meet new people or make new friends. Maybe that's not accurate and it's just the environment of the "real world" that restricts people from making more friends. Unlike the children's world where you are surrounded with other children around your age with similar interests (e.g. just having plain fun), you have adults that range in a much larger age group that have a more diverse set of hobbies/interests.
I'm not saying this is a positive or negative. What are your thoughts?