At best, it is an average measure of the undergraduate student body's opinion regarding the best universities in the USA.
I attend one of the world's best universities, and whilst it is certainly not easy to gain entry to the ANU, it is easier than probably all the universities on that list, and even a couple of other Australian ones. Very, very few people would argue that Monash provides a better Arts degree than ANU, especially in the Political Sciences, International Studies, Anthropology, Archaeology or Language fields, yet the marks needed to enter ANU are lower than those for Monash. The core reason for this is the fact that Monash is in Melbourne and the ANU is in Canberra. Very few people would agree that Canberra is a better city than Melbourne