Why dont alligators attack when walking down a path?

i was in everglades national park couple of years ago walking down the main path, and they were on either side of the pathway without a fence to protect the park visitors. nobody seemed concerned, but that false sense of security could stem from the visitors expectations of public safety. something you cannot take for granted in most parts of the world. what's the story here? do alligators hate asphalt? or the heat coming off the asphalt? or is it that intrinsic respect that most animals have for humans? i couldn't find a ranger to ask before we had to leave.