You’re spending too much time complaining about the height of one particular tree and not enough looking at the forest.
Of course it is the case that rating employee value is often very difficult. The entire point of the famed book “Moneyball” was that in an incredibly public industry like professional baseball, where people’s performance was rather starkly quantifiable, people paid to hire and fire workers (players) still kept getting it wrong. Lewis’s message was, hey, in MLB is imperfect at this, how good is YOUR industry, where you can’t always easily count stuff like home runs and errors?
In general, however, most people are paid what they are worth, and a class of employees will be paid very close to what it’s worth.