Student
government, much like
homecoming/
prom royalty, is nothing more than a
school-sponsored
popularity contest. Most high school students realize that their
student government is that in name only, having no real
authority. No matter who they vote into these
artificial positions, it will still be the
teachers and
faculty that run the school.
So, the kids do what they would have done anyway, and vote for their friends. Naturally, the "popular people" win, having more friends who vote for them.
Why do schools do this? By helping to emphasize who is popular, they are only doing harm to the less popular people.