There's losing sight, and then there's trying to find it. I remember a short video where a toddler was wandering straight for a road, and someone happened to prevent a tragedy, and mom came running out of the house as the camera was still rolling.
People were calling negligence, what a terrible mom, yadda yadda. No, that mom was running around the house looking for her kid, frantic as time passed. You just don't think they can open the door that early. Manipulating a door latch or knob is a developmental milestone, plus, what if the door didn't properly latch? Mom could just as easily looked outside first, but that would be counterintuitive.
Also, "I thought you had him/her?" Is a real thing.
Curb weight base f150 in 2000 was like 3900, 2020 was 4700. Nowhere near 6000lbs as far as I can find. Bigger? Absolutely. Heavier? Not by that much.