Example: 8 years ago we moved to a small town where no one picked up their dog crap in the park except me. The local ascetic said, "That won't do any good. No one else does that."
When people saw me picking up after my dog, they started doing it too. Soon there was no dog crap in the park. There was no requirement to pick up, but people did it because it made a better park for everyone. Just because some people steal, doesn't mean everyone will join them. Most people will do the right thing because it usually makes everyone better off.