You are right man
I see the MCAT as a soccer game in a league, every time you face a different opponent the; results of the game will be a combination of the strength of team you are facing , Your Skills, How you perform during that game, and Luck
Even the good teams who have the best players and best skills get bad results some times, it all depends on what happens that day during the game.
I don't know If that is fair for a test which is a door for medical schools, however remember that those tests are not godly made and that humans like me and you built this test
From what i learned is that Life is Not fair and we just need to cope with it..