This is why modern parenting guidance tends away from a blanket stranger danger policy toward something a bit more nuanced like "beware of a grownup who approaches you or initiates a conversations with you, but if you are in trouble, almost any grownup who looks safe to you is probably someone you can ask for help."

You can add a few more layers like seeking out someone in a uniform or who has a stroller, but generally speaking most people minding their own business are perfectly safe.