When I had my first child, I was still working full time and he was in daycare. My husband's job was closest to the daycare, so I only drove him a few times a month, unless my husband was traveling for work and wasn't in town. On at least two separate occasions that I remember, I forgot that my son was in the carseat, which was in the center of the back seat. My commute was about 40 minutes, and the turn for his daycare was about 10 minutes before I would arrive at work. He usually fell asleep during the ride, and so he wasn't making any noise, and as I got closer to work, I was already going over the meetings I had scheduled, my deadlines, etc. However, both times I forgot he was in the car, I realized he was there BEFORE I got out of the car. Either I spotted him in the rearview mirror when I went to exit the highway, or I spotted him when parking the car, or I remembered him when I stopped thinking about work and started focusing on the present again. My point is, one can forget the child is in the car if distracted, but there comes appoint when you stop being distracted, maybe just to park in the correct spot, change lanes, or simply as you unbuckle your own seatbelt or close the car door. Given that RH had gone to breakfast and interacted with the child right before getting to Home Depot, I don't see any way that he would have been so caught up in his own distractions, plus I don't think little Cooper would have fallen asleep in that short period of time, and wide awake toddlers are not quiet; they are hard to ignore.