Social commentary that isn't far fetched. A small amount of negative imdb commentors project themselves into the situation and get frustrated. I don't understand them getting annoying by comparing what is basically a slasher with chavs, to ones own survival fantasy and logic. Logic in a fictional movie? This movie isn't even meant to be a real story, it's meant to have realism to it. Somehow this confuses people? The realism was the reflection of society within the characters. The story was illogical at times and simply moved us from A to B for entertainment and pace sake. I'd have liked a better story myself but it wasn't to be, and it wasn't the main motivation of the movie anyway. If you wanted a real story it would probably have been two people hiding in a bush for a very long time.
I think this movie just made people uncomfortable for some reason.
The ending made perfect sense for me because the main villain had himself played out a violent revenge fantasy . It left us with obvious answers about environment and upbringing, but also gave us some more questions about personal responsibility, morality, culture and ego.

It's sad that backwards horror characters, once an appropriate setting in dark places of the USA, are now well placed in Britain. The main good guy characters could have had a little more weight to them so we cared about them.