I tend to agree. That said my DS now 27 decided at 4 1/2 years old that it was a lovely day and it would be really nice to let himself out and go for a walk down the street barefoot and in his pyjamas holding his cereal bowl in one hand while I who had just given birth to his brother was bathing the baby.
I realised he was gone quite quickly after bathing and changing, but still enough time had gone past that he had completely disappeared. Some very good saintly person had picked him up and dropped him at the local doctors surgery. The police were very good, but strangely never came out. I was a crying, screaming mess. My mother had to take over.
Anyway when I turned up to collect him from the doctors surgery I'll never forget the withering, despising look the reception staff gave me. Completely understandably. I didn't even bother to explain. It didn't help that I still had my slippers on and my hair was a complete mess. I looked completely like a deranged, incapable person.
My mum had to take over as I was a nervous wreck for two days afterwards.
So I'm prone not judge too quickly. Could possibly be the parent was away and left the child with relatives or something or parent has severe PND or something.