It sounds like there was some filtering to try to prevent that, for example, filtering out people who follow both Harvard and Stanford. Interesting anyways, even just to see what people interested in attending certain schools are interested in.
I was kind of in a similar position a couple years ago. I didn't do an internship at Amazon, but I was considering joining full-time, and was really unsure of whether to accept (I had great offers from a couple startups, which I was mostly focused on at the time, but a friend at Amazon was really pushing for me to join).
In the end, I decided to go with Amazon, thinking like you are that I could always change jobs if I didn't like it.
And yeah, I hated it. Absolutely hated it so much that I quit two months after joining. The problem was that the other startups I was interested had filled the position I'd been looking at (I'm more of a data analyst than a software engineer, and data analyst positions are a little more rare), and now every other place I'd interview at would think I was a total flake. I'd interview somewhere, and I'd have to spend 30 minutes explaining to multiple people why I left Amazon so soon and how they'd know I wouldn't do that again at their place.
I'd have great technical interviews, and I would get told this, but people would be worried about what kind of employee I was simply because of this one mistake I made joining Amazon.
So yeah. Hopefully you'll have a much better experience than me, so that even if you don't like Amazon you can always change jobs, but just throwing my own experience out there as another data point.