That's WHY it happens. It doesn't make the stupidity "excusable". But she wouldn't have made this mistake if she had the option of switching off the airbag and keeping the baby beside her. Why aren't we allowed to make these decisions for ourselves?
I have no problem with being allowed to make such choices for ourselves. I still maintain that she is responsible for what happened and nobody else. Let's put it this way - if you were on a jury sitting in judgment of her, and her defense was that she forgot the child due to seat laws, would you find in her favor based on that defense?