Rose,
Good point, never thought about that before.
Here is a safety issue the would say the right side of the vehicle is better for a fuel filler.
It is more common for a woman to climb back into a vehicle during re-fueling during "bad" weather. With the filler on the passenger side, you would be less apt to climb in the vehicle since it is a long walk. If you do get back into your vehicle, you are more apt to touch the vehicle while walking to the other side therefore grounding yourself out reducing the risk of fires caused by static electricity.
Women are more likely to have that happen then guys because guy clothing is primarily natural fibres (wool, cotton, leather, etc) and womens clothing are more synthetic fibres (nylon panty hose, rayon blouse and skirt, patent leather shoes, etc.)
So one could look at it as a safety issue for the good then for the bad.
Tom