I had this all the time when I ran a toddler group - as long as they were safely out the door with their pushchair and child, they wouldn't bother to close the door behind them. It drove me mad - the worry that a child would escape when my back was turned.
You see 3LF that's exactly the thing. I was talking to DD1's teacher about stuff assuming (stupidly) that DD2 (2 yrs) was safe within the premises. Next thing I know I see her out of the window tootling off out of the gate and down the path.
Why are people so chuffing up their own arses that they can't appreciate that other people use the nursery.
For those that rightly say that DD2 is ultimately my responsibility I can say in my defence that she had taken herself into the nursery room and still had two cloakrooms to get through before escaping into the garden and then another gate to get through before she was out of the boundary.
Also, why don't people stop children when they see them going it alone? I guess collective responsibility / care is a thing of the past.