Most universities set a minimum attendance requirement — commonly 75%, though some programs run as high as 80% or as low as 65% — as a condition of being allowed to sit the final exam. Miss the threshold and you can be marked "detained" or "ineligible," regardless of how well you know the material.
The rule generally traces back to two things: regulatory bodies (education boards, professional councils for fields like engineering, medicine, and law) mandating minimum classroom contact hours, and universities protecting themselves from the fallout of exam-eligibility disputes by enforcing a hard, auditable number rather than a subjective judgment call.
From the institution's side, attendance is also treated as a rough proxy for engagement. It is not a perfect one — plenty of students learn well independently — but it is objective, easy to track, and easy to defend when a parent or student challenges a grading decision.
The practical takeaway is that the rule is rarely negotiable in the moment, but it is very easy to plan around if you track your numbers early instead of panicking two weeks before the exam-eligibility list is published. Checking your running percentage every couple of weeks with a bunk calculator turns this from a crisis into basic maintenance.