Some time ago our local paper ran an experiment in town. They got a ten-year-old to pose as a lost, upset child in the town centre to see what people would do (it's OK - her mum was close by with the photographer and the police had been informed). So many people just walked by, it was unbelievable, and I wondered how they would react if their own kids got lost. Clearly you've seen the other side of that and had to put yourself in a potentially difficult situation, because these are the sort of parents who will equally accuse you of trying to molest their child.
There were some interesting observations in the experiment, but what was sad was the number of passers-by who, when interviewed afterwards, said they'd been too scared to get involved, either because they thought the child would turn round and attack them or because they didn't want to be accused of anything. Such a sad indictment of our society when you have to question your own instincts.