The Detroit case (Tarajee) is definitely more heinous than the Virginia case. I've heard of people forgetting they left a child in a car before, and it always annoys me that there are people who could be so stupid. But when I heard about the woman in Detroit, I was horrified. I'm sure she didn't mean to do it, but her actions were so identical to a purposeful act that legally it has to be murder. If I hold an anvil in my hand, hanging outside of my 12th story window, and then let go of the anvil to scratch an itch, it's murder, even if I didn't intend to let go of the anvil, and even if I didn't mean for any pedestrian below to get their skull smashed. It's not like she had 13 kids and lost track of them. There was absolutely no mitigating factor in her case at all. The only thing I don't really like is the "without possibility of parole" part. But then again, her two dead kids don't have that possibility either.
I would definitely see an unfair disparity if the facts were switched and she still got murder.