What is the main barrier to obtaining car insurance for female drivers?

In the United States, there is currently no barrier for anyone, man or woman or teenager, to obtain car insurance unless they don't own a car, are less than 16-18 years old (driving age), or are prohibited from operating a motor vehicle as a result of license suspension or other penalty, in which case they don't need a car or cannot drive. Laws in other countries may differ from the United States. In Saudi Arabia, women are not allowed to drive at all.