I'm not a particularly religious person. However, I think it's likely that the Almighty, if he/she exists, has some pretty severe punishment lined up for the inventor of the car alarm.
Here's my reasoning. I hypothesize that the overwhelming majority of the time that a car alarm goes off, it's not supposed to go off. It's annoying 100% of the time, especially in a dense urban area where lots of people have the priviledge of hearing about the fact that a leaf fell on your hood.
Even in the rare cases where somebody really is trying to steal your car, or from your car, we're so desensitized to the alarms at this point that we don't care. If I saw somebody breaking into a car with an alarm going off, I'd think it was the owner trying desperately to turn off that damn malfunctioning alarm before the neighborhood goes nuts!