I'm not going to try to drag out the references, but bone density is not directly hormonally related. It is, however, related. Bone density differences start in childhood. Boys tend to be more competitive and participate in physically demanding activities. They are also more apt to have ADHD issues. Girls tend to be more cooperative and sedentary. How many girls normally ride skateboards, bicycles, and are seen running around in their everyday goings-on? Bone density is directly related to skeletal stress.
IMHO, these are issues that no amount of social engineering is going to change. Accept it. Girls and women have skeletons that are more lightweight as a result.
There were times before household conveniences such as washing machines, vacuum cleaners, etc. where women had to hand wash the family clothes, drag out the rugs and beat them with a stick. Those were the days when it was likely that most women involved in such drudgery didn't face a future of osteoporosis. They died early because they were physically worn out and had lower resistance to diseases and infections, and were slower in healing.
Regarding the cell phone distraction issue, women tend to be more socially involved (husband, kids, parents, friends) and feel the need to stay in communication at times when men don't tend to do so as strongly.
Those designing safer vehicles would do well to try to design in features such as air bags that don't kill at distances closer than 12 inches, telescoping adjustable steering wheels, foot pedals that aren't mounted at a fixed point, seat belt harnesses that are more considerate of feminine anatomy (maybe a system that senses the weight of the driver and passengers, and sets the mount points of the harnesses accordingly). Large-breasted women will always be at a disadvantage in the auto safety situation if they choose not to wear the chest-crossing belt (but if the chest belt top mount point can be adjusted, that may help).
But progress will move forward and things will be safer, if the past compared to the present is any predictor.