Every student has the same homework, teacher and class usually. If one student works hard every day and night until summer vacation, meanwhile another simply doesn't do anything, how could it possibly be fair to penalize the first student for the second one's laziness? It's simply absurd to give everyone equal chances if they don't want nor deserve so.
I am in two minds really on this but as it says student I take that as an older learner (late teens) than a pupil (child).
In that case I think as long as the opportunity is available to all performance will vary based on commitment and those committed will be rewarded.
With children it is a different story as they can generally not be expected to have their future interests at heart.
Why, exactly, are schools arranged like factories? Kids are pushed through in age-defines bundles, and only those who "excel" have any real chance of an actually good college. If, instead, we organized students by intellectual ability and coherence, we would have both a bond between students, and those who need individual attention might actually finally get it.