I've read several times that the average grade at Harvard is A-. Grade inflation has become so normal some places that grades don't tell one much about how one student compares to another at the same institution.
They aren't all geniuses and they all didn't work equally hard.
https://www.youtube.com/watch?v=5rz2jRHA9fo
Brandon Marsalis briefly touches on that subject in this clip (Warning - some mild profanity)