Why do the doctors prescribe Seroquel when it is NOT approved and raises risks in elderly?

It is a Psychotic Drug. Dont use it unless the person is going to be dead next week anyway or the person is Completely out of control. From what I read, that particular drug is sold on the street for hallucinations and a drunk feeling that can put a person to sleep for days. When the Doctor prescribed it to my mother for depression, no way throw it away. After a meeting with the doctor he agreed to give her a muscle relaxer enstead.