It isn't public - none of these universities publicly say, "You can donate 2 million and we'll let your kid in". Which was the amount at Stanford in 2012 (at least based on what someone I met working in admissions told me).

It's left unsaid because it's better for the brand to pretend that this isn't a thing and that just because your parents gave money or because your parents are famous doesn't mean they'll let you in.