Why do you prefer working at the back?
When you work in a place like that you soon find out that if you have the option to avoid contact with customers take it and run. I'm being biased because when I worked at KFC we had to take orders and pack them. It wouldn't be as bad now with secondary teams packing the orders after you take them assuming the store you work at has this. When you are working around customers every little thing you do is being scrutinised, the customer is always right and when you need to do something you often can't because a customer is waiting to be served. Some people may enjoy this but it's not for me I would rather stand over a sink and wash up all the trays.