I was berthed in Portimao Marina, Portugal, some years ago and went in a hire car to a big Supermarket on the outskirts of town. The parking area was a very short walk from where the Supermarket and it's rows of trollies were situated. Having finished shopping I sat in the car and watched as someone who was almost certainly a refugee/migrant from North Africa patrolled the car park. When Mr & Mrs Portugal had unloaded their trolley into their car, our friend went to them and offered to return the empty trolley, which saved them a 150 yard walk in the hot sun...He earned 13 Euros in the short time that I was there, returning the trolley and extracting his tip of 1 Euro when he clipped the next chain into the trolley lock.
Full marks to him for business acumen and I did notice that he wasn't chased away by the ever present security man. I suspect he saved the Supermarket a fortune in preventing the disappearance of trollies abandoned in the car parking area.