Store boxes

Has anyone actually been allowed to take home the empty mini brands boxes from stores? I was at toys r us today and there was an empty box so when I went to purchase my items I asked if I could have it and the cashier was super rude and literally snatched it out of my hands. I don't see why it's such a big deal for me to ask if I can take the empty box and the fact that the cashier was so rude about it left me with such a bad taste in my mouth. I'm just curious on others experiences with being able to take the boxes or not being able to take them.