It's for sure that academics didn't get them into B&R.
I think most of the cast didn't get in through entirelly legal means
My bet is on that this is one of those
fictional type of schools that exists to cover that pesky "requirment" of the upper class to have a diploma. Not all the rich have particularly keen children when it comes to intellect and willingness/dedication to learn.
The really prestigious schools won't allow them to pass, would ruin their reputation, no amount of money could afford that, so they need something of a less prestigious one which in turn can be less scrupulous as well. That can basically take a bribe in the form of a hefty donation for a pretty much guaranteed diploma. Now these type of schools usually have a solid cover-up in the form of regular students, which is required for more than one reasons, and they offer good education nonetheless but there are double-standards in effect.
Actually everything i've seen so far about this school, how some students behave and what they can get away with makes me firmly believe that this is one such school. That acts as regular college but it gets by (and possibly built upon) the donations of rich families in exchange of guaranteed diploma and by offering high-quality-of-life services to their spoiled bra-.. *cough* children.