A few years back, I was waiting for the light to change at 51st Street and Fifth Avenue in NYC.  As I stood there, an elderly south Asian man came up next to me with a cart loaded with breakfast food that he was delivering to a meeting. When the light changed we both moved forward.  As he pushed the cart, he did not see a small gap at the edge of the sidewalk. His cart wheels got stuck. He continued to push, the cart toppled over, and the food (still in its wrappers) spread all over the road.