The only thing I can say is you are not paying attention. Nearly every time I have seen a gator near a public area in WDW, which is frequently, it has only been a matter of time before some one throws food at it.I have never, ever heard of guests feeding alligators, so let's just stop that nonsense. If it's happened, then it's a once a year type thing. With today's media I've never seen photos or videos of guests close enough to feed alligators.
Also, there is nothing you can do to keep the gators away. Like deer, there just apart of humans and our habitat.
It seems to happen everywhere.
I live on a lake and we get gators in it from time to time and I have lost count of the number of times I have seen my idiot neighbors throw food at them.