Family Dollar

I go to this store every day that I get off work an I do have a backpack that I wear so they want me to leave my backpack up front witch doesn't bother me cause I know that's not a great area an I never have trouble with employees putting my backpack behind there counter but when I go in there, but today when I get off work I ask the lady if she would put my bag behind the counter an she rudely tells me no that i can leave my bag right there witch is by the door. This store has a lot of bums an druggies that goes in there an she wants me to leave my bag by the door so if someone wanted to they could easily walk of with my backpack cause the employee isn't gonna keep an eye on my bag that has my purse, medicine, wallet, an money.. If the rules are u have to take your bag off that's fine but if a customer ask u nicely to put it behind the counter so nothing happens to it cause I know there's cameras behind the register then what's the issue an why be rude about it?