It's a really bad UI for a disruptive message that gets pushed to millions of people.

How many people know what amber alert is? Of those people, how many know what to do about it? Of those people, how many know what Nissan Versa looks like?

How much harder would it be to change the text to something like "Child abduction alert: if you see <car color/model/license plate> call 911" (and, perhaps, include a silhouette of the car model they are looking for)