Probably something along the lines of: Without accommodation, being able to learn, participate, and demonstrate competency in a series of courses which presume a student's mastery of information presented through secondary education.
And so the answer is that colleges already can and should take into account % learning through GPA.
I was imagining that the good school presented more and better information, (perhaps more at the style and pacing of a good college classroom,) While the poor school may not have even presented all the information, or done so in a rushed way. (Focusing on that majority of students bound for community college.)