Grocery store register people who are clueless about bagging items. It's like they've never shopped for their own groceries. No, the chips and expensive eggs do not belong flat on the bottom with heavy bottles of laundry detergent on top. Even if lightweight items are durable, it's better for the heavy stuff to go on the bottom because that way there's less chance the bag will tip over during the trip home. I'll unload the heavy items first onto the belt, light items last, but some will resist packing until they get to the light items. Maybe they want me to pack, except if I'd wanted to do that I'd have used the self-checkout.