In Denmark today 0-2 year olds are regularly left outside in a baby stroller to nap while their parents are inside.
Edit: I think a lot of people in this thread are getting the idea that I'm advocating parents need to helicoptor parent their 2-year olds 24/7. Not at all what I'm saying. I don't think you are greatly increasing risks to your child in that scenario.
Shows a toddler in Mongolia--probably younger than two--tethered to a bed in a tent all day while her parents work in the field. She gets checked up on at lunch time when her parents come back (and probably other times).
Such actions are routine in other cultures.
In both cases you usually don't see whether the parents left their child intentionally or not.
Whatever the real reason, harassing the parents is quite a judgement based on a statistics with sample size 1.
Point I'm making is directed at the study, which contends that our moral judgements should have no impact on how we assess the risk to a child. Even though I think our morals are heavily skewed and unnecessary, I bet they at least point in the correct direction of what the risk to a specific child is as compared to the average statistical risk to all children.
Your comment seems culturally biased. See the movie Babies? The Mongolian baby Bayar was often left alone for hours.
My point is that the parent who is accidentally negligent most likely is providing their child with a safer environment than the parents who intentionally leave their child alone.
BTW have you even had a 2-year old? I doubt very much there was ever a point in history where 2-year olds were left with zero supervision. Sure it might be an older sibling or some other community member watching them, but I can't imagine how someone feels leaving a 2-year old alone at home is a reasonable thing.