I don't know how EB is run over there, but over here, they offer soemthing noone else can even hope to match - 7 day right of return for any reason. It's to encourage you to buy in the first instance, completely risk free (you can even ask for money back).
The general consensus in NZ is not to allow software or music returns due to piracy. Or so they say. But EB allows returns for ANY reason. You can say I finished teh game in one week, and I don't need to paly it again, and they'll porbably take it back. It's their policy, and they honour it (though they reserve the right to refuse if you abuse it).
Thing is, I'm guessing, it's a double-edged sword. What happens to returned games? They must stick them on the shelves and sell as new. They have been played, but not kept. As long as the return isn't about a defective product, and it's about not liking it during the trial period, they probably consider it as new.
Maybe.