I had a guy approach me on my college campus a couple of semesters ago while I was walking to class and asked if he could make a quick call. I was skeptic at first but he offered to make the journey to class with me while he called so I let him.
Where do you live?Otherwise, they can go to a nearby payphone and call collect.
FWIW I'm from the South where everyone waves to everyone. I never "loan" my phone to a stranger & have been asked several times. Never.
This is a little different but I took my 1958 beetle to a car show about 3 hours from my house. I used the gps to find my way there. Then seeing my beetle doesn't have a radio I listen to pandora all the way there. When I got there I took some pics of the cars at the show. Well about half way through the day the phone went dead. So I asked over 20 people if they had a iPhone charger. No one owned a iPhone or that's what they told me. Which I find hard to believe. Eventually some dude who was cool has hell let me just barrow his juice pack he said just find me when your ready to go. It was a good thing cause my junk broke down on the way home. Not all people are bad or want to steal your phone they just may be stuck. Hell they may have there own iPhone that's just dead.