I saw three separate dealers take (in some cases extraordinary) measures to get the attention of a customer who had walked away from their booth without collecting the change from their purchase. I'm sure that they were experienced businesspeople who know that there's no benefit in keeping the money in the long run, but even so, they could have simply done nothing, and it was heartwarming to see them go out of their way.
I didn't see it, but a friend told me about a cosplayer who, when asked to pose for a picture, said something to the effect of "sure, but let's move over here so we won'