dog eat dog, survival of the fittest etc etc etc
Another comparison to dogs is we're kind of like beaten dogs that have learnt to go against their instincts out of fear. With so much being illegal we can be torn between assisting and fear of reprisal for breaking a law. Since the decline of communities where we knew everyone it's now easier for us to turn away from someone who needs help because we don't know them. So there's another indication of possible manipulation which plays on our natural instincts.