JtS did a good job of answering. I would add that my experience as a wildlife rehabilitation worker is that wildlife do often use city streets, but it's not quite so frequent for people to see them because it's something something that would tend to happen at night or around dawn. So the fact that they are present in this area tells me that they do use the city streets from time to time. As JtS pointed out, though, the alligators can be seen on the streets during the daytime.