Yes, I'm absolutely against tracking for teenagers or adults but I could see it when my son is around 8 years old and I let him walk to a friend's house or go to a nearby playground. We live in Hong Kong, and it's very safe here once he's old enough to understand the rules of the road and be careful when crossing.

Having something to track them between 8 and 12 years old I think is useful. I remember when I lived in Japan (where children start walking to places as early as 5 years old) before the iphone came out, there were plenty of children phone that sent gps to the parents and only allowed calling to a select set of numbers.