First of all, there may be financial reason why a student has to work, regardless whether or not they have a car. There are teens who work out of necessity, whether it be to help the family pay bills or make ends meet or purchase necessities for themselves such as clothing, food and personal items. Some teens must work in order to insure they have money to go to college. Fox does not even consider those kids who, out of necessity, are required to be financially independent. Likewise, she does not realize that some teens, out of necessity are required to have cars. Not all parents are in position where they are able to chauffer their teens to "orthodontist appointments and basketball practice." Some students live outside the bus routes and have no other way of getting to school every morning.
Second, the author does not take into account the positive aspects of teens having jobs.