Proposed this argument to a teammate the other day after practice, thought it would be interesting to hear peoples thoughts.
Although there are more AA spots in xc, there are a lot more people you're competing against to even grab a spot to nationals. Once you have punched your ticket, now you're competing with 55 other individuals ( not mentioning the runners who qualified as part of a team ) for one of the 35 AA spots.
In track, there are only 8 spots for AA, but the field is much, much smaller. Making it to Nationals as an individual for track is arguably harder than cross, but earning a spot on the podium is also an easier feat than in xc.