When I pack my own supermarket shopping, I ideally place items in reusable bags where it's easiest to put them away. Hence I carefully pack items in different bags where 'aroma' from soaps or washing powder doesn't contaminate goods like meat and dairy products. Eggs are another item which travel far better at the top rather than the bottom of a heavy bag. I also, logically tend to pack frozen and chiller items together as they keep each other cool, and well away from anything hot to avoid spoilage.
However I think many supermarket packers are school kids or first- job youngsters and they have never had to do their own shopping and are blithely unaware of these niceties. Frozen stuff often goes in the same bag with hot roast product and moreover it is jammed into as few bags as possible without any regard to breakages, torn wrappings and general product crush damage. On one occasion I caught a young packer deliberately squashing a loaf of bread so it would fit into an already full bag to save using another! I complained to the checkout woman, another loaf was brought and I just stopped the packer doing exactly the same mangle-to-fit procedure again. I think the young girl obviously hadn't a clue why I complained. Yeah I like to pack my own groceries by myself.
