Many years ago, I went to the grocery store with my son. He was about 7. I asked him to put the cart back up by the entry to the store. He left it on the ramp and when he turned to walk back, the cart turned and started following him. The faster he went, the faster the cart went. It seemed to be targeting him. I wished I had a video camera to record that. He was terrified that the cart was coming after him.