Another child dies in a hot car ????

I just read eight children have died this year so far in hot cars,pretty much all of the parents say they forgot about the kid in the back seat,being a father of two i just don't understand how you forget,while you are driving you look in the rear view mirror,you can always see the car seat and child in the back,i just don't understand how you can just forget you have a child in the back seat ????