Ever find yourself sitting in a classroom before the lecture begins watching others come in and sit down? I also bet that after an exam you would find yourself comparing whether you think you did better them or not. Everyone compares themselves to others in some respect. I know that I have a hard time not wondering how I fall in the grade break down compared to my classmates.
There are two different types of social comparison. The first is upward comparison where we compare ourselves with someone who we view as superior to us. The other is downward comparison where we compare ourselves with someone we view as inferior to us. Both types of comparison have the ability to either boost or hurt our self confidence.
Sometimes social comparison can be motivating or inspiring. For example, say my friend that I consider to be fairly comparable to me gets a good internship, that could encourage me to find an internship as well. http://thumbshots.files.wordpress.com/2008/01/social-comparison.png
All in all, social comparison will always be a part of our lives.
Good opening that all of us can relate to. You provided some good examples!