These two photos with the captions tell the whole story.
It reminds me of when I was at a self-serve gas station one night. I pulled up and started filling up my tank. I was going to go inside and pay once I had filled up. While I was pumping, a older black man drove up to the pump next to me. He started to pump the gas, but the man in the store would not let him.
He came on the intercom and said he needed to pay first. I was shocked. I could only think this was because I was a younger white kid and he was black. What else would explain this behavior? It made me sick.