Realistically, they probably didn't even know they did it. You would have to come into the parking spot next to this blue(ish) car pretty hot to do that and somehow not hit the concrete wall in front of you. This looks like a long, slow scrape than a really old person, with no onboard sensors, would do. They were stopped in that spot, just grinding on the blue car back and forth until they decided they couldn't get in the parking spot and left. Their grandson discovered the blue horizontal stripe on their white Buick the next day...they have no idea who hit them or where it happened.