Let me see if I understand this. An old man walked across a busy street but not in a cross walk. He vanished behind a mailbox, then re-appeared right in your path.
Where was he before he appeared in your path? Behind a mail box – either he was exceptionally small, the curb was exceptionally tall, or you didn’t notice his head sticking up above the mailbox. And before he got to the mailbox, where was he? He was walking across a busy street. You didn’t notice him in the street.
Both of you were walking without paying attention to your surroundings. I think there’s enough “in the wrong” for both of you to have some.