Even if commissions were forbidden, workarounds abound. For example, top performers could be promoted to higher-paying 'team leader' positions that they kept only so long as they remained top performers, and the bottom 10-25% could get the axe every fiscal quarter. In some contexts, getting to keep your job is indistinguishable from a bonus or a commission.
While I fully recognize the potential for corruption in admissions with an outright commission structure, academic departments and the executive suite bear some responsibility, as well. If Admissions is signing up students who are not ready, willing, and able to fulfill the requirements of their programs, then Academics should dismiss those students. If Academics fears the wrath of Administration and waters down programs in order to keep attrition rates low, then the problem originates in the executive suite and not in the admissions representatives' compensation structure.
CWE