Well it is understandable why it need to be 18 years old and above, more mature and have more flexibility than under 18, also my advice for under 18 focus on study first..oo..abit pricey la I think. but for those who can save up money can la. i hope all ages are eligible for this especially students who are need extra money to study.
Anyway it is good that you would like to yourself some income for study, so go ahead and register for it..its okay u can try to save money slowly, think of it as like an investment for business. all the best to u