Simple paranoia
You should all read this:
http://freerangekids.wordpress.com/2008/04/06/why-i-let-my-9-year-old-ride-the-subway-alone/
I did, and I think that woman's insane.
My son will never be crippled with dependance. But neither will he be the victim of abuse, injury or abduction simply because of my own carelessness.
In my job, I see children all the time who are injured, quite often (in my opinion) due to parental neglect or simple carelessness on the part of the supervising adult. It's not all about abduction, it's also about injury due to the carelessness and insensitivity of people who drive too fast in residential neighborhoods, let their dangerous dogs wander the streets, etc.
But either way, I think that woman is insane.