Were the men in the workforce better off building the bridge?

In the beginning of the movie the show practically the whole contingent of previous prisoners died. It seems like there were less British soldiers who died while they were building this bridge that the last, I think they even mentioned there was more than one workforce that all died.

Did collaborating with the Japanese actually save prisoners' lives, or was this something we were not supposed to think about?

Or was this story just some kind of psychological study or movie that had nothing to say about anything and was just a peculiar story about whistling POW soldiers?