If the games industry didn't want used games sold, they would tell EB and Gamestop to stop and they would have to. Remember, game companies can get retail corps to do things with even the hint of not letting them sell their merchandise.
With such high game prices and such low margins for the retailer, game makers have to let retailers resell or there would be not enough profit to stay in business, and that would lead to less places to buy the game maker's games.
