I do wonder if some people (especially men) would be wary of even going near someone else's child because of the social stigma of child predators and abductors. I'm sure it's hard for those who would want to check or help but are worried if the parent came back right away seeing them break the window for a baby they'd assume the worst and not trying to help. So I don't know if it's really about people caring more about animals than babies. Most people wouldn't assume you're trying to steal a dog if you're breaking into the window of a car. It's unfortunate that so many seem to be paranoid these days and less trusts breeds fear and indifference.
This is a key part in the decision making of many men. Most babies/young children, aren't left in a vehicle alone and the car used had dark tinted windows, so the thought would be that there is someone inside with the baby in this case. Animals, for the most part, are left alone in vehicles and lots of people go up to a car just to say hi to a dog, especially a puppy.
So as an experiment this failed for obvious reasons.