Norms. Same thing for women’s bathrooms. Unless you are alone in there, the psychopath is going to face multiple women yelling at him to leave.
As a society of laws we like to think we can solve everything by just writing a good law. Sometimes it’s much better to create situations where strong norms can solve the problem without the need for law enforcement. Norms are like laws where everyone is an enforcer.
The issue with psychopaths is that although they may be rare, they can have an outsized impact. It only takes one of them to victimize hundreds of people and create an atmosphere of terror.