It actually works great for them - by the time the fraud is revealed, the workers are long gone, the records who worked on what and who's responsible are conveniently "lost" and the manager in not responsible for anything - they always had the correct paperwork. Nobody to blame, "mistakes were made", let's forget it and move on. And the workers are not stupid either - they would pick up what is expected of them very quickly, and will know it's ok to lie as long as you aren't caught for enough time.