The thing is that customers don't have to stop all at once. If one restaurant stops all on its own then it will go out of business. If a customer stops tipping

The thing is that customers don't have to stop all at once. If one restaurant stops all on its own then it will go out of business. If a customer stops tipping then they suffer no consequences cause they are freeloading off of everyone else who hasn't stopped yet. Once the rest of the customers see that people are freeloading off of them then they will be tempted to stop too.