Being watched makes people safer

Criminals don't like being watched

It's safer to be in an environment where the act of committing a crime is likely to lead to arrest and punishment. If people are being observed then if a crime takes place it is likely that the police will be able to make an arrest. If you are in an environment where there are no potential witnesses then this might be a dangerous environment because it is attractive to criminals. If everyone in an environment is being observed by the public then this will act as a deterrent to crime.

People who are able to form voluntary alibi agencies will be able to protect themselves from crime because it means there is a much higher deterrent to crime.