Actually, I was going to see another movie, but the audio of it failed. Trying not to waste that couple of hours on something else, I ran to Netflix to find another movie.
I kinda read what it was about and decided to give "Sam Was Here" a chance (I like movies that include deserts and lone protagonists). I shouldn't have done it.
The movie is like a bad (and doubly extended) episode of "Twilight Zone": apparently, a mysterious red light in the sky turns all California hicks into masked killers, and Sam had the misfortune of being in the wrong place at the wrong time, nevertheless, the whole film is a total nonsense and no explanation is given.
Tip: if you saw this movie, don't ask yourself about the meaning of it (you won't find it), just forget it and keep going. If you didn't see it, don't ever do it.