They need to start raising money for college, their car, and/or any school activities. Also maybe there is something they need to reach a dream they have and they want to get it now before they have too many responsibilities.
There are two profits of doing a part time job 1st you will get experience and 2nd you will become independent and able to earn. The confidence level increases in you after doing a job. Some schools and colleges have very tight schedule and you can't able to do a job but some have a time table which allow you to do a part time job so choose your school or college carefully. You can click top college section of blog.oureducation.in for getting information about top college of India
Money. It teaches them responsibility and how to be a good employee (by showing up on time, doing work, dealing with other people one may or may not like, even bosses), and it looks good on college resumes.