Hi , as you know AFMC is a government college which is under indian army and in order to get admission in AFMC you need to appear in NEET UG exam . AFMC is a government funded college that's why it's fees is very less and before joining college all AFMC students sign a bond of serving the army  as short service commission for 7 years. The bond amount, 29,00,000, is to be paid by candidates if they fail to provide their services as Medical Officers.
So in a way it is students choose  to work as short service commission in army for seven years.
Hope this helps