Thoughts on Car Alarms

The other morning, at 3:30, a car alarm went off right outside my open window. It was quite annoying and I got to thinking, as nobody turned it off and I considered going to check that it wasn't my car. Car alarms are not useless, but don't function properly in our society. If they did, then your little clicker on your keychain would also start beeping and tell you to get out to you car because someone is trying to rob you. I understand that part of the point of the noise is to get anyone to look at it and therefore scare thieves away, but the thing is, a smart thief would just say "it's my car, I'm locked out" and everyone would believe him/her because that's what we do.