AirTag location accuracy issues

I know this subject has been brought up a million times, but I'll ask again. I have three air tags. Two stay with my son. One is on his key chain so we can find if he loses his keys. The other is hidden in his car trunk. He has an iPhone 14. When wanting to track the location of the keys or car, many times the "find my" app will say that the keys or the car are still home (or some other location) when they are actually with my son who might be miles away. This incorrect location can go on for hours. As mentioned, he has an iPhone which would be feet away from the air tags so shouldn't they both be pinging their location using his phone? I even made both sharable with him thinking that would help.

Thanks,

SAL