There are safer ways to encourage independence.
Not allowing a young child to play alone in a shopping centre playground, unsupervised, with their even younger sibling in tow, is not helicopter parenting.
The media play on the stories of missing children - of course they do. It's the media. What's scary is the amount of stories which you DON'T hear. Stories which I have heard myself, which mean I will never, ever risk placing my child in a situation which could lead to their harm. Statistically, the risk might be low. But any risk is too high for me regarding these issues.