Yes, cost per line of code itself is an error.

Only cost for effective* outcome matters. And if your lines of code have a cost, you would want fewer lines of code to achieve the outcome, not more.

Are you sure you disagree with that?

* If your place of work starts talking "efficiency"**, run. Find somewhere the conversation is *effectiveness* — at the goal/outcome level.

** Not to mention that "efficiencies" is MBA speak for "right sizing" away effectiveness.