It's much more strange to me that people WOULD let strangers use their cell phone. Back when it was just a phone, sure. But now it's my wallet with all of my credit cards and banking loaded on it, it has all of my passwords and all of my OTP apps and codes, it has the ability to unlock doors in my house (and for some people to open and start their car) it contains all of the contact information for everyone I know, it effectively has every email I've ever sent or received and every picture I have ever taken or been sent, it has access to publish content as me on trusted social media profiles. Yes, obviously all of this should be protected by much more than just physical security. But we all know that software locks can almost always be broken if you're in possession of the physical device.

I happily help strangers when I can, but I'm not going to hand over the keys to my entire life, on the most fragile and expensive object I probably have on my person.

Its not at all strange that you cannot use my device that has access to some really important personal info on it. It's rude for me to hover over you while you are talking on the phone so I can make sure you aren't snooping through my messages, email, etc, and I'm not about to let you use a device that has access to those unsupervised.

There's too much risk to hand a stranger your cell phone, unfortunately. They can steal the phone, call some high cost number, venmo themselves money, who knows what else.

I think it depends on how you phrase it, there's a big difference to me between asking somebody to place a call on behalf of you on speakerphone, versus asking them to physically handover an unlocked smart phone.

I'm very reluctant when people ask me for the reasons others have said.

Not saying you didn't do this but I'm much more likely to help when someone comes up with a clear and concise statement of the problem and a minimally intrusive solution ("hey, my phone is dead and my wife has the charger, could you call the Hilton on speaker and ask for Room 123?" or even "could I log in to my Facebook for a second and send a message to my friend saying I don't have my phone but I'll be at Starbucks, you can hold the phone?")