There are two aspects to this that should be considered.
1. Is this work that the person didn’t finish during the day because of poor focus?
Or
2. Is the person being asked to do more than what is reasonably expected in a 40 hour week?
If it is 1, then people should suck it up, if they didn’t waste time at work, standing round the water cooler or chatting to the person next to them, they would get their jobs done in the time allotted, so they shouldn’t get anything.
If it is 2, then this is where you should showing the boss the valuable contribution you are making and working to increase your salary. If there is no project bonus or no forthcoming pay rise – move on.
In the end, you only get paid what you are worth. If you stay around being underpaid, then that is your choice, no one forces you to do it. If you can’t move because you are under qualified or not experienced enough, then do something about it.
It is all a question of motivation.