Zappo
Explorer
Well, the creature can't just eat each other; the energy to live has got to come from somewhere. It's more likely that there's an entire ecosystem underground. Probably, the surface is blasted by too intense light for too much time to start evolution there. And that's assuming that most of the planet is a desert, which is the kind of Star Wars simplification which would hardly apply to reality. After all, the only planet we know for sure has advanced life IRL presents all sort of wildly different climates and morphologies. Maybe the monsters evolved somewhere else and migrate through the tunnels, or something like that. They aren't any more implausible than Aliens.
"Only works in sunlight" isn't completely stupid. The eclypse only comes for some time every 22 years. So the planet is bathed in sunlight for, what, 99.9% of the time? And no clouds either. Why should the vehicles have batteries, since they would never be used? Batteries are costly, bulky, and not terribly reliable after such a long time.
I agree, though, that it is unlikely that the colony's destruction wasn't discovered in 22 years. There are good explanations, but none that is so evident that it didn't need be shown in the movie.
"Only works in sunlight" isn't completely stupid. The eclypse only comes for some time every 22 years. So the planet is bathed in sunlight for, what, 99.9% of the time? And no clouds either. Why should the vehicles have batteries, since they would never be used? Batteries are costly, bulky, and not terribly reliable after such a long time.
I agree, though, that it is unlikely that the colony's destruction wasn't discovered in 22 years. There are good explanations, but none that is so evident that it didn't need be shown in the movie.