It's not a non-answer. Good managers need to figure out what metrics make sense for the team they are managing, and that will change depending on the company and team. It might be new features, bug fixes, new product launch milestones, customer satisfaction, ad revenue, or any of a hundred other things.
I would want a specific example in that case rather than "the good managers figure it out" because in my experience, the bad managers pretend to figure it out while the good managers admit that they can't figure it out. Worse still, if you tell your reports what those metrics are, they will optimize them to death, potentially tanking the product (I can increase my bug fix count if there are more bugs to fix...).
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I heard lines of code is a hot one.