The child is only three years old. Chances are, the neighbors never saw her for the first 2 years, as she wasn't old enough to play outside alone.
I imagine that these old folks had this child dropped in their lap--something they never suspected would happen when they bought their home. (We all get the idea that the kids grow up and move out and our parenting days are over --what a joke!) I further suspect that the fact that this neighborhood has a "no child" policy is why houses don't sell very fast.It looks to me like the biggest mistake they have made is letting the kid have a Big Wheel. (And if I were a betting person, I would bet that the druggie mother provided that, trying to assuage her guilt over dumping the little girl.)
In truth, with the demographics in Florida, it makes the neighborhood more desirable.