As you understood from the beginning of the story, a part-time job often brings only problems.
A teenager hasn't got enough time to learn lessons, help the parents with chores and even sleep.
In this case he's turning into a tired and unsatisfied with the life person.
In addition every age has own prerogatives.
If you're an adolescent you schould work in order to support your family.
In this case the process of learning will be hard, even odd for you as a job will exhaust you.
In contrast the getting a good education is a main aim for a teenager!
There are few children in their teens who can combine study and a job.