The existence of tipping in the US contradicts this theory. Why tip 20% as a non-returning customer, when it is in your own best interest to tip 0%? Still, near

The existence of tipping in the US contradicts this theory. Why tip 20% as a non-returning customer, when it is in your own best interest to tip 0%? Still, nearly everyone does it. Luckily, empathy and/or social pressures are important for most people, which causes them to make choices that are not 'game theory optimal', but better for society.