This programme has just started over here in Aus and we have not had that one yet. THe one we had this week had a 3 yo who would just wander out of the house whenever he felt like it. The mother said to supernanny - he does this all the time and I then have to roam the neighbourhood to find him!!!! For goodness sake - lock the front door I thought. How can you be totally oblivious to where your children are!!!
In the part when the sn is away and they are left on their own - the 3 yo took off and no one knew where he was. He was wandering the street, stepping out and crossing roads without looking - totally oblivious to the danger. The parents had no clue where he was.
When the supernanny returned she let them have it and simply put a $5 chain on the door that the kids couldn't reach so they could not just wander out of the house when they felt like it.
I think that the parents I have seen so far simply take the easiest option rather than wanting to put in the hard yards and then are surprised when things are not what they want.