Attendance in BITS Pilani has been quite a debatable topic. The reason behind it, as I see it, is to allow for students to study with their own methods and times. There are friends of mine who prefer to study on their own by using the slides provided by the professors because they feel that they can cover it faster or better on their own than in the classrooms. This freedom allows them to use their time more efficiently. This happens very rarely though and the professors, more often than not, urge the students to attend every class.
Sometimes a student might want to study a course he/she is not taking, so, due to this they can just go and sit into any lecture of their choice. Also, if you don’t get a professor’s lecture section during your timetable preference then you can still attend those lectures at your own leisure.
But, mind you, the zero attendance policy is restricted to lectures only, and the professors may assign some marks for attendance for labs. The other side to it is that sometimes, the students just stop attending the lectures for no reason and waste their time in a less fruitful way. Once it becomes a habit, it is very dangerous for academics.