As someone who has mostly lived in hot climates, I have never understood why all our homes here in the South (Gulf Coast) have black roofs. I want to paint mine

As someone who has mostly lived in hot climates, I have never understood why all our homes here in the South (Gulf Coast) have black roofs. I want to paint mine white badly, but I am afraid it will look terrible. I'm also confused by my HVAC return air duct opening at floor level instead of ceiling. I only use heating a few weeks out of the year. But the climate is such that A/C is needed often for dehumidification as well as temperature control.