The difference is that the university will sell out its admission spots for its own benefit, but doesn't want its agents to sell said spots for their own benefit.

A university will happily tarnish its illusion of 'meritocracy' for the right amount of money - as long as it is the beneficiary. It's not going to let its employees tarnish that image for personal gain.

Life isn't fair, and neither are admissions (Although the universities try their best to convince children and the non-thinking otherwise.)