My first thought on all of this? Wow, it must be nice to have never, ever made a stupid mistake in your life. It must be so comforting to be able to cling to that sense of superiority because you've never had a forgetful moment or been distracted.
I'm going to go against popular opinion here and say that I do, actually, have a great deal of pity for parents who unwittingly and unintentionally leave their children in hot cars. The key words in my sentence being "unwittingly" and "unintentionally." How could I not feel pity? A stupid, thoughtless, careless moment, and your child is severely injured or killed? As horrific as it is, and as unthinkable as it seems -- how do you forget your child? -- we don't know what the circumstances were. New parents, unaccustomed to keeping an eye out for their child, unaccustomed to the routine of day-to-day life with an infant, could easily have a moment of carelessness and forget their child in the car. A parent who isn't normally the caregiver could likewise forget. Overtired, overworked, overwhelmed, people forget things, even extremely important things. Perhaps their day was already horrible -- a loved one died, a pet had gone missing, their house burned down, a dear friend was in a car accident -- and their child was the furthest thing from their mind. Do I think they should be punished for their forgetfulness? Yes, definitely. But I'm glad that, in this case, they weren't punished by the child's death. Many others are not so fortunate.
Now, this burst of anger and frustration at the feeling in this thread stems from one painful moment in my life, where I nearly killed my younger cousin. I was babysitting three of my cousins, all under the age of five. I was a teenager, and an extremely responsible one, at that. By this point I'd been a nanny for five children (in one family, all under the age of ten -- what a handful!) and considered myself to be fairly mature and capable. I put my youngest cousin in the bathtub, with only about an inch or two of water. The other two kids were in the bathroom with me, "helping" me out by distracting their brother (who didn't much like baths), when there was a sudden loud crash from the kitchen and then the fire alarm started going off. Forgetting my cousin in the tub -- even though I knew perfectly well that a child can drown in very little water, and I also knew the other boys weren't old enough to be responsible for their little brother -- I raced out to see what the problem was. Wiring or something had sparked a small fire in the kitchen, which I was easily able to put out myself. When I got back to the bathroom, my baby cousin was face-down in the tub. Now, I was lucky, and he survived (without any ill effects, thank god!), but I still have nightmares where I fail to revive him. It's not exactly the same thing as forgetting a child in a car, but it's similar enough. I was responsible for my cousin. I knew he shouldn't be in a tub unsupervised. I left him alone anyway. I should have taken him out of the tub before racing off to see what was wrong in the kitchen, but in that moment I didn't think -- I just acted. And my cousin nearly died as a result.
I suppose I shouldn't be allowed to breed either, huh?
Now, for people who deliberately leave their children -- and pets -- inside a sweltering car because the child's or pet's presence would be an inconvenience to them, I have no pity whatsoever. I have pity for the children and the pets (and, in one case from last summer, the helpless elderly woman who was left by her family), but not for the caregivers. They're the ones who shouldn't be allowed to breed (or own pets, or be responsible for the care of other living beings), not the people who made a stupid, honest mistake and paid a terrible price for it.