Thanks for your feedback - I'll take a look at how we can improve the copy. The idea is that yes, in general you know who is looking after your child - being able to call the with one click is just a convenience. However, in the abnormal case where your child is away from their carer for some reason then the ability to be notified immediately and establish contact with the carer could be the critical difference that stops your child from being another of the thousands of children that go missing every day.
Once you add in the complexity of two working parents and a reasonably large care network - then the conveniences become more valuable as well.