I encourage everyone to read before you knee-jerk people as stupid parents who shouldn't have bred.
Issues of how this happens is perhaps parent is out of routine that day, i.e. not the parent that usually has the kid.
With the air bag issue the kids are now in car seats in back seat.
And we have the electronic distractions, ala cell phones & devices. Parents have been distracted by an issue at office they are discussing in car.
Fatal Distraction: Forgetting a Child in the Backseat of a Car Is a Horrifying Mistake. Is It a Crime?
....."Death by hyperthermia" is the official designation. When it happens to young children, the facts are often the same: An otherwise loving and attentive parent one day gets busy, or distracted, or upset, or confused by a change in his or her daily routine, and just... forgets a child is in the car. It happens that way somewhere in the United States 15 to 25 times a year, parceled out through the spring, summer and early fall. The season is almost upon us.
Two decades ago, this was relatively rare. But in the early 1990s, car-safety experts declared that passenger-side front airbags could kill children, and they recommended that child seats be moved to the back of the car; then, for even more safety for the very young, that the baby seats be pivoted to face the rear. If few foresaw the tragic consequence of the lessened visibility of the child . . . well, who can blame them? What kind of person forgets a baby?
The wealthy do, it turns out. And the poor, and the middle class. Parents of all ages and ethnicities do it. Mothers are just as likely to do it as fathers. It happens to the chronically absent-minded and to the fanatically organized, to the college-educated and to the marginally literate. In the last 10 years, it has happened to a dentist. A postal clerk. A social worker. A police officer. An accountant. A soldier. A paralegal. An electrician. A Protestant clergyman. A rabbinical student. A nurse. A construction worker. An assistant principal. It happened to a mental health counselor, a college professor and a pizza chef. It happened to a pediatrician. It happened to a rocket scientist.
Last year it happened three times in one day, the worst day so far in the worst year so far in a phenomenon that gives no sign of abating.
The facts in each case differ a little, but always there is the terrible moment when the parent realizes what he or she has done, often through a phone call from a spouse or caregiver. This is followed by a frantic sprint to the car. What awaits there is the worst thing in the world.
Each instance has its own macabre signature. One father had parked his car next to the grounds of a county fair; as he discovered his son's body, a calliope tootled merrily beside him. Another man, wanting to end things quickly, tried to wrestle a gun from a police officer at the scene. Several people -- including Mary Parks of Blacksburg -- have driven from their workplace to the day-care center to pick up the child they'd thought they'd dropped off, never noticing the corpse in the back seat.
http://www.washingtonpost.com/wp-dyn/content/article/2009/02/27/AR2009022701549.html