To my mind, the responsibility for transportation on a teenager old enough to get a driver's licence is on the teenager. We do not provide a bus as a perk, it is a necessity, but it is not anyone else's responsibility to give a teenager a better ride to work. If you want a car, earn the money to buy a junker. Why should the parents spend their money on a car you don't need? The bus is free and it gets you to school! If you want to improve your transportation, make it happen. Don't put it on the school or the parents.
I realize that this doesn't help with your essay, but it is my opinion. I think you would be better off focusing on problems with the bus system itself, on drivers, on bullying and student problems. It's hard to afford a chaperone for each bus that the students will actually obey.