Why do professors take roll?

In almost every course the professor requires that we be present in class and, to make sure we are, takes roll and awards points accordingly. This logic baffles me. Students pay a lot of money to attend college; we are, by all intents and purposes, adults. Why should any of us be penalized if, for whatever reason, we decide not to show up to class? Anyone who has gone to college has had at least one professor that lectured almost word for word out of the text book. What, then, is the advantage of attending that course if you can read the textbook?

Recent studies have shown that class attendance bears no reflection on grades. It is widely known that people learn at different speeds and in different manners. For some, reading texts is the only way to procure knowledge; others find lectures the key to their grades. So if I absorb information better by reading the text at home, what is the advantage for me to attend class?

As I am an adult I decided to approach one of my professors, who happens to be my age, in an attempt to discover why they had chosen to apply this rule. I got no justifiable response. I started to wonder if the reason was related to the professor’s ego. Perhaps professors need to have a full classroom to feel they are performing their duties as an educator correctly.

No matter what the answer I feel I am wasting valuable time in certain courses. In what other institution do you pay for something then be penalized for not attending?