I don't like it but U.S. courts do not consider party donations, or even more direct benefits, to get contracts bribery unless there's explicit evidence; B following A does not mean A caused B unless the people involved say so, even if there's a clear pattern.
I think it's a corollary of their misguided "money is speech" interpretation of the 1st amendment. A university admissions bribery case is unlikely to benefit from such 1st amendment arguments.
