Souls that are already here are trapped and farmed in an eternal cycle of reincarnations.

New souls that might come to this planet don't come willingly but lured here.
See the thread of "truman's past lives regression" in the first page of the soul traps thread.

I found amazing how this movie called our planet a "deadland" even indirectly as i have also decoded what the brain/cerebrum=cerberus symbolizes and is all about.