If a CFO knows which days the dumpster is emptied, you have a strange CFO. The metaphor is to point out that there’s a lot of technical details that aren’t tracked (like usually refactoring isn’t tracked independently) and shouldn’t be tracked because they are the normal part of the technical job. A CFO can’t measure it even if they wanted to because nobody else is measuring crazy things, like how fast you walk to the bathroom or any other metrics that are specifically related to doing your job.