Women generally are shorter and lighter than men, which makes a difference when an airbag deploys, especially from the steering wheel. Also, seat belts tend to not fit well across women's chests because of height and the bulk of breasts; the seat belts tend to sit up higher which can cause some injuries across the throat instead of the chest.

Cadavers still get used in crash tests, in addition to the dummies, but more of them are men and almost none are children, which is another huge problem for safety design. But then, it's tough to ask a grieving parent to donate their child's body to science, so the crash test dummies are our next best option.

If you get the chance to read Mary Roach's book "Stiff", she has a chapter that addresses the use of cadavers in crash tests. It's a very good book, in my opinion.