I think if you flip that thinking, there'd be people spreading the word that the prevention is minimal and the punishment not a serious deterrent. e.g., no one thinks "I wonder what happens if you're busted grabbing stuff out of a shipping container?" But if there's no punishment, word would spread fast. "Those guys have been doing it for weeks and no one cares. X got busted but they had to let him off light. They don't do anything about it!"