It isn't quite true that student loans can't be discharged through bankruptcy. Student loans are not excluded from discharge if excluding the debt would "impose an undue hardship on the debtor and the debtor's dependents":

11 USC 523(a) Exceptions to discharge ... (8) unless excepting such debt from discharge under this paragraph would impose an undue hardship on the debtor and the debtor's dependents, for -- an educational benefit overpayment or loan made, insured, or guaranteed by a governmental unit, or made under any program funded in whole or in part by a governmental unit or nonprofit institution; or an obligation to repay funds received as an educational benefit, scholarship, or stipend; or any other educational loan that is a qualified education loan, as defined in section 221(d)(1) of the Internal Revenue Code of 1986, incurred by a debtor who is an individual;

Per http://www.moranlaw.net/student_loan_brunner.htm, "undue hardship" means '(1) that the debtor cannot maintain, based on current income and expenses, a "minimal" standard of living for herself and her dependents if forced to repay the loans; (2) that additional circumstances exist indicating that this state of affairs is likely to persist for a significant portion of the repayment period of the student loans; and (3) that the debtor has made good faith efforts to repay the loans.'