Because people seem to be more afraid of guns in Florida than in most other states. Even "pro-gun" people are afraid of people carrying guns in Florida, that's why you can't get unlicensed open or concealed carry passed.
It's not that way in Washington state, either. I can walk right up to the school building doors open carrying if I want to, when picking up or dropping off my daughter. And, if I am attending a school function, I can leave the gun locked in my car on school property.