I had a neighbor across the street walk to my truck window as I started my back in, and asked me if I was ok, did I need him to back that in for me. I had literally just started moving backward with my wife watching the rear. I smiled and said, "nope, I got it." He watched for the two minutes it took me to finish the job then silently walked back to his site. Yeah, helpful and nosey....fine line.
If I see someone clearly in need of assistance I will offer a set of eyes. That's about as far as I go. Many times I've added my flashlight to the mix when folks come in at night (and no, shining at the truck does NOT help!). I let others figure things out on their own. It's called learning. It's why we're here.