People need to understand that if you have the ability to forget things like milk, bread, stamps, cellphone, keys, etc.; you DO have the capability of forgetting (or losing awareness) that your child is in the car with you. Our brain doesn't necessarily assign "worth" to what we forget or not.
As far as the number of cases where children are left alone in vehicles....90% unknowingly and 10% knowingly. Very different than most people believe; or should I say the exact opposite of what most posters have expressed in this thread.
Originally Posted by Play Care:
I forget milk, bread, stamps, etc. I've never forgotten my kids. 
But, I do think in rare cases, it's a truly horrific accident. The one that comes to mind is the teacher who returned to work after the summer and forgot to go to dc, because she had never done it before.
But I do think their are parents who are do it purposely and claim accident. Even more so now since we have the knowledge.
I do call parents but I would hate to be required to.