SJS, believe it! People do even dumber things than that. They leave infants outside stores in strollers without even a four-year-old to watch them! I personally know someone who told me that he once saw his sister-in-law’s kids (all under age 5) outside a store on a busy street in Boro Park by themselves and walked off with them – took them to ice cream. The mother was hysterical upon finding her children missing (who knows how much later she realized it?) and I think she didn’t talk to him for a very long time. I hope that it at least taught her a lesson. I’ve been tempted to do the same thing many times.
People also leave their children alone in the house, something that I cannot fathom. I once saw a young couple in my neighborhood taking a Shabbos evening walk and asked them who was watching their infant (I figured their parents or siblings must have been there). They simply smiled and answered, “Hashem.” I mean, yes, their bitachon is beautiful, but that is horrendously irresponsible!