I get what you're saying and I myself am guilty of surface level learning. But the idea that students should consume all the information is impractical. Learning what is acceptable to discard is part of being a student. I imagine very few students read every college text book cover to cover.

Beyond that people have different motivations and goals and only a limited time to achieve them. Basically I wouldn't be so quick to judge. Plenty of students have dropped out and gone on to do impressive things and that's a bit beyond reading only the abstract for a few assignments.