I don't see how you can compare interviews at companies that do different things against each other in terms of difficulty. In fact I don't even know what this means for interviews within the company. For instance, Amazon: is it a difficult interview for a programmer, any technical person, or even for a marketer? If it's for a software engineer, is it as difficult for new grad entry positions as it is for higher positions? Which is being evaluated?
This comes to mind mostly because I'm surprised at who ended up on the list in terms of tech. Palantir, for instance, is indeed one of the hardest interviews out there, if only because the variety of programming questions they ask you is so large.
Salesforce on the other hand, while not a cakewalk, is definitely not on the level of difficulty of a Google or Facebook technical interview, at least for their university hires.
Lastly, I'm glad to see Teach for America up there. It's become a pretty competitive program to get into and this just further proves it, and I hope it gets expanded so more people can be out there doing good.