I believe it relates to being able to approach a gate agent and having them rebook you on a later/tomorrow flight as a courtesy, after you checked-in but missed

I believe it relates to being able to approach a gate agent and having them rebook you on a later/tomorrow flight as a courtesy, after you checked-in but missed a flight because you dozed off, didn't watch the time, had a medical issue, couldn't find the gate in a huge airport, missed the connection from an inbound flight, etc. Really it's an extension of the US customer service ethos.