The purpose of Ivy league schools is to keep the institution alive. Self preservation. There is nothing fair or even sensible about who gets in and why. It's supposed to be a mystery; a dream you can either achieve through insanely hard work or get in with the right social status or deep pockets. How is this different than anything else in life, or throughout the history of time? If someone's dad can donate a new library and to their jerk off son in, why wouldn't an institution do that? They're private!
Their success lies in a combination of insanely smart students, alumni admissions, "rich kids," and that applicant who's uncle had an affair with so and so and is a personal favor. Education isn't about being "fair" or discourse or any of that. It's to buy a career, into a network (Ivies have large private equity / money ties), or to get a license that is regulated (engineering, nursing, teaching, etc.)
I went to engineering school. I did summer school at my hometown college ("better") than my Alma mater. And guess what? They were both ABET accredited. Same in difficulty. The only difference was the zip code. People went to the prestigious school to get a better job and into a better alumni network, better job placement, etc. That's why you go to Stanford instead of State U Engineering School.
We have to stop kidding ourselves that education is about actually learning. If it was, then we would get rid of college football teams and send everyone and their mother to community college or a trade program. The point of college (in the USA) is to in-debt 18 year olds, dangle carrots in front of them (new houses, cars) and make them slave 9-5 for the rest of eternity.