that probably describes a lot of people in tech megacorps too
It certainly wouldn't benefit anyone who hires people if those people could estimate their own contribution, or, god forbid, compare it to their compensation. I think there's a term for the difference which now eludes me.
The floor is mostly arbitrary (see the wage collusion scandal between Apple and Google for an example), and then beyond that it's a question of who is the most productive, effective at getting things done, etc.
So while they do have "something to measure," these metrics can be uncorrelated with profitability - or even negatively correlated with it. It's possible for a productive team to spend their time on an unprofitable project, while another team barely works but ships a profitable product.