Now go ask the factory worker, truck drivers, delivery drivers, &c. who are tracked minute by minute up to the bathroom break

As code monkeys we have it easy but it's far from the norm

For some jobs, hours worked isn't a practical measure of productivity or value. I used to pick orders in a warehouse. The more hours I worked, the more orders they shipped, the more orders they could take, the more profit they could reap.

Now I work as a data analyst. I have some required duties spelled out in my position description, plus a catch-all "requests from other divisions as assigned." If I'd spend more hours working, nothing would really change. The only guaranteed value for each hour they're paying me is having me on call that hour. Which is worth something, I guess, but good luck calculating it.

Output vs median employee?

I could argue that some weeks I work 300 hrs, some weeks 0 (feels like -60) hours.

To bill my hours, I estimate them within a range. Then I move the needle depending on my productivity and the value I delivered.

I'm afraid it's not precise. It's more of a happiness-based metric (for me and the client).