When my 2nd child was born we all got ready to go out. We hadn't taken him out much so got my older child and the baby dressed and ready. Put baby in the carseat and put him on the couch.
Then got older child (3) ready, wellies on, coat, juice cup etc...
The routine we had done with one child for almost 3 years.
Went outside, locked the front door, got half way down the street when we remembered the baby.
It's not that people 'forget'or are careless, they are just on autopilot.
Have you ever driven somewhere so oftwn that you realise youre half way there without even really thinking about directions?
Theres a part of your brain that just takes over.
In alot of these cases something out of the ordinary has occoured and routine has been disrupted.
It's really sad.