Well, normally they use the call to get to know if the older people have something of value in their house. They usually tell stories that there has been a heap

Well, normally they use the call to get to know if the older people have something of value in their house. They usually tell stories that there has been a heap of crimes lately in the area, and that they'd like to help the people to secure valuable stuff. If they have, they'll show up after some time, and collect it, to store it safe in the "police department" (which they don't, of cours). Or they'll show up as two, and one will pretend to do some questioning, while the second walks around the house and searches the rooms to find something of value. That's at least how's written in the newspapers. So yes, it's a scam that is far more targeted, and not that easy to do - because you have to be physically in the area. Or you need straw men.