To rent a car you must have liability insurance.
A car rental agency will sell you their liability insurance for $10 a day, only if you are not a resident in their state. So if you are visiting FL and only have a FL drivers license they will not let you sign up for their liability insurance.
An insurance agent will only sell you non-owner insurance (no vehicle owned) if no one in your house owns a car. So if your staying with a friend temporarily, you must be on their policy.
So if you only have a FL drivers license, and your going to stay with a friend in Florida, you cannot get liability insurance therefore you cannot rent a car.
Why are things so complicated in America!? We have the best, hard working, smart and ethical people in the world. Yet the worst rules and regulations.