I think you're still missing something, it's also not about "getting lucky" (though in real life, yes, that's often important), it's about someone who has the p

I think you're still missing something, it's also not about "getting lucky" (though in real life, yes, that's often important), it's about someone who has the power to reward you, knowing what you've done, intentionally rewarding you with much less than your friend who did the same things as you. That's what they are measuring. The subjects in the experiment can see that the experimenter is observing the work they are doing, and can see how the experimenter consistently rewards the other subject differently. It's much more like when people at the workplace can see how much money their colleagues are making, while having visibility of what each other is doing, and noticing that some are getting much more money at the end of the month (which is one reason employers try as hard as possible to hide their employees' salaries).