I've seen this kind of trend in the software industry. Let's say there's a guy who performs well, Joe. And there's a guy who delivers mediocre work, Calvin.
Now as Joe keeps performing well, he gets assigned more work than his colleague. He gets better increments at the end of the year (not always but it's the expected trend) and that gets him earning more than his colleague.
However, a time comes when Joe cannot take the increasing workload anymore. At this point of time he either quits and desperately tries to reduce his responsibilities (I haven't heard of anyone being successful at this as such).
If Joe does try to get his responsibilities reduced, by talking to his manager and telling him about the list of things that he has on his plate and about how many of them he can actually manage, then the managers shrug it off. I'm from an Asian country and I've frequently heard about this justification given by managers : "Hey! You earn more than your colleague. So you have to deliver more work too for it".
Is this something that's acceptable? It's like the top performer has no choice but to keep hopping jobs because there are bosses who're constantly pushing everything onto his plate until he's left with no choice but to quit.
I have two questions about this.
1) Is this reason an acceptable / valid reason to load more work onto a colleague?
2) If not, then what responses can a person say to make a defense for his work-life balance?
Edit: Added some more info. Can I take it up with the HR about my boss telling me that he's assigning me more work because I'm paid more?