Ok, let's look at this objectively.
This is from
MindefIf you are between 13 and 16.5 years old (WEF 15 Aug 2006):
You need to apply for an exit permit if you intend to travel or remain overseas for 3 months or longer. If you are remaining overseas for 2 years or longer, your parents/guardians will also need to furnish a bond, in the form of a Banker's Guarantee of S$75,000 or 50% of the combined annual gross income of both parents for the preceding year, whichever is higher.
If you are above 16.5 and have not enlisted for NS:
You need to apply for an exit permit if you intend to travel or remain overseas for 3 months or longer. Your parents/guardians will need to furnish a bond, in the form of a Banker's Guarantee of S$75,000 or 50% of the combined annual gross income of both parents for the preceding year, whichever is higher.Before this case, there was a cut-off date whereby pre-enlistees must commence their course of study before the age of 17 and 1/2 years. This means that only those who are born in the later months of the year (e.g. September onwards) have a higher chance of deferring successfully. This is regardless of whether you can pay the bond or not. Hence, this discriminated even those who can pay the bond.
However, Mindef has since changed the deferment rules to allow all males aged 16.5 years and above to defer, as long as they can pay the bond. This is a positive change, since all males, regardless of their birth month, can defer to pursue further studies if they wish to.
Why the bond you ask? See it as a collateral, like a mortgage when you ask for a loan from the bank. It is to deter pre-enlistees from chucking their Singapore citizenship and not returning to fulfill their NS duties. It is a token of goodwill if you like, an assurance that you are sincere about returning to serve once you've completed your studies.
I understand that this policy may seem to discriminate against the less well-to-do in Singapore, but you must understand the potential threat to national security if some sort of controlling mechanism is not in place.
Furthering one's studies is a personal choice. You can choose to defer first and serve later, or serve first and study later. At the end of the day, we still have to fulfill our national duties.