My first thought ...

... was "at least they remembered to take the child out of the vehicle.

I walked out of Sam's Club and the car next to mine had the back door wide open.  My imagination had the mother lifting the child out and juggling an oversized purse.

I had just finished loading groceries into my car when a woman came out of the Sam's Club liquor store with a 4 or 5 year old. I had already closed the door to her vehicle so that 

I wouldn't hit it. 

I mentioned it to her. As it turned out, her young son let himself out of the vehicle and took off without closing the door .