I'm a woman who spent my school and college years working in retail, mostly in stockrooms. Because of my looks (short hair, rarely wear makeup or jewellery, etc) people never had a problem with me working in the stockroom, lifting heavy boxes and such. I don't understand the thinking behind it, but basically the prettier and more well-presented the woman, the less she would be allowed help out in the stockroom.
There was one teen girl I remember who was kick ass at martial arts, but liked to wear pretty clothes and makeup to work. She was so strong and fit, but the manager always made her work on the tills, despite her protests. I'm not sure if it was that he wanted her on the floor because she was pretty or wanted her out of the stockroom because she was female and therefore weak in his eyes, but either way it was annoying.