As a former member of Student Government, I can say this. I was never very popular, and most of the Student Council at my school was comprised of the "smart kids" at school. We never did anything of major import. We decided on what shape the year's parking sticker would be, and sold parking spaces to the students. I didn't even get bribed for a better spot!
The only thing even remotely useful that we did was to regularly meet with the school superintendent, albeit in a solely advisory capacity. We made no decisions to affect the school. We didn't advise the school board. Our suggestions were routinely ignored by the administration.
Student Government is supposed to give students a microcosm of elections and parliamentary procedures. Ostensibly, we learned to work to build consensus. Since we didn't have any actual power, what we largely did was agree with anything anybody suggested. That and raise funds for an annual trip to the Student Council Convention in Chicago.