Always put the trolley away where it belongs, either in the car park trolley bay, or with excess trolleys beside the bay, or directly to the trolley person if times right, or inside the complex in trolley bay, pending which direction I am going.
But if I see someone leaving a trolley out elsewhere and I am in ear shot, they will be called out to, to stop being lazy and put the trolley away.
Then I walk out and pretend to be writing down their details - No' plate and time etc, that usually gets them doing the right thing.
Gotcha scum bag!