When I was a teen, my mother worked for a company that returned magazine covers to the publishers once they were out of date in retail stores. The body of the magazines were discarded. Only the covers were accounted for. The stores received a credit if the covers were returned. The body of the magazines were tossed as trash. Note: this was before recycling. I used to ride my bike over to her workplace and sift through the debris, then ride away with a box filled with comics or any other magazine I might like (free). Read a lot of Marvel and D.C. in those days.