Not familiar with Florida law but it's pretty common everywhere I've been. You can thank the hooligans who like to cut the air hoses making it more expensive for the gas station to provide the service. Usually if you buy your gas there you can go in and ask them to turn on the air compressor and they will.
You could always carry your own hand held air pump with you and pump up your tires as much as you want and anywhere you want, or you could buy yourself a few cans of air. When the situation is put into a context where you are actually a participant it is easier to see reasons why for example a gas station would charge to air up a tire.