"Exact same" represents a grammatical practice that is particularly prevalent in American English; the use of an adjective for an adverb. In this phrase "exact" modifies "same" and is functioning as and adverb.
In the literal sense "exact same" is indeed redundant, however, words aren't quite so precisely defined as apparently your teach would have you believe. If I have a Hugo Bos blue shirt with an 18 inch collar, someone with a Hugo Bos blue shirt with a 20 inch collar might think we have the same shirt. In fact, someone with a Hugo Bos white shirt with a 20 inch collar might think we have the same.
You might even argue that if they are two shirts identical in every respect they are still not "the same" shirt. If I wore my shirt today, and again tomorrow, you might tell me "you're wearing the same shirt as yesterday", and that would be absolutely literally true.
Which is to say, "same" is used rather more loosely than "the identical object" in common language.
By modifying it with "exact" you are emphasizing that they are even more "same" than if you did not so modify.
Many words sound like they are absolute, binary, and not subject to gradation. However, I am reminded of a discussion between Sheldon Cooper and Stuart the comic book guy on the hilarious TV show "The Big Bang Theory":
Stuart: Ooh, Sheldon, I’m afraid you couldn’t be more wrong.
Sheldon: More wrong? Wrong is an absolute state and not subject to gradation.
Stuart: Of course it is. It’s a little wrong to say a tomato is a
vegetable, it’s very wrong to say it’s a suspension bridge.
It is common to answer a "Why...?" question with "Because..." or indeed another phrase that isn't (overtly) a full sentence.
However, the answer then implies the entire proposition being questioned from the original question.
So e.g. in the following sequence:
"Why do my plants die?"
"Because you don't water them."
the answer implies: "Your plants die because you don't water them".
So in your sequence, the answer would imply:
"People read books because people read books to get information."
Now, the answer is not ungrammatical and could potentially just about express what the speaker really intended to say (e.g. they may have meant "People generally read books because they see other people reading books to get information").
However, it is pragmatically odd and unlikely to express the intended meaning. They probably intended simply the meaning of "People read books to get information". In which case, the appropriate sequence would simply be:
"Why do people read books?"
"To get information."
Best Answer
This is Indian English. If you are talking to the rest of the world you should check out
Mind your English. Otherwise it's fine.