When I was teaching English in China, one student got locked out of his apartment. Apparently, the city has authorized locksmiths you can call to open your apartment after proving that it's you. So he called one and was shocked at how quickly the locksmith could open the door.

The locksmith said to him "Locks aren't for people like me. If someone wants to break in, a lock isn't going to stop them. 15% of people will try to steal no matter what you do. 15% will never take anything even if you leave your door while open. Locks are for that 70% in the middle that will steal if the opportunity is right."