Going from license plate to phone number would be one hell of an endeavor in most US states.

I expect the US police to have this capability; < 1% expectation that they would share it with a random citizen who walked in.

“Powerless to help you, not powerless to harm you.”

I don't quite understand the question. If she had had her phone, she could have called the driver using the information from the didi app, but she had no phone, so she didn't know who to call.

Herself, I’d have thought.

Her phone doesn't ring.