My son lives in a sketchy neighborhood, will it allow him to locate his stolen truck?
Yes, if the stolen truck is around other iPhones. It may not work in rural areas with low population density.
I've turned off my phone, then drove and parked the car in Boston. Then left and when I go home, I turned it on and it was able to provide a location better than the car's locator (BMW.)
I've used it when I checked in my luggage, I was able to track it until it was loaded in the aircraft. The next update was when it was unloaded, the final was as it was loaded on the conveyer, and down the pickup.
If you look at the latest AirTag news, thieves at attaching the AirTag on expensive cars so they can track the car to the house. Then they steal the car. (When it is left outside.)
What would really be stupid if the thief has an iPhone.