No, Anna university does not give more marks for more pages. The Anna University system as a whole cannot be blamed for the wrongdoings of a few individuals.
In college, you will encounter both types of professors. Some professors never assign notes or self-study topics that exceed 40 pages in the entire semester. Because it is a government college, some professors would only attend 20 of the 45 lectures during the semester.
Another side of the coin is that some professors will only give you marks based on your answers, regardless of how many pages you write. One could receive the highest grade simply by providing appropriate answers for 30 pages or receive arrears for writing irrelevant material for 40 pages. Everything depends on the professor who handles the paper.