There's this awful strain in left-wing thought which suggests that people only deserve to be rewarded for the effort they put in, as their natural endowments are taken to be morally arbitrary. This thesis is particularly dominant in some primary schools, where kids are more likely to get awards for effort than actual achievement. It's quite ridiculous.
As a personal anecdote: when I was about 11 or 12 years old, my teacher gave me a 'B' for maths on my report card. Since I was top of the school, I found this rather puzzling. So I politely asked my teacher, "Why did I only get a B? I got everything right, didn't I?" She answered, "Well, sure, but you didn't exactly try very hard, did you?"
The underlying motivation for such try-hardism comes from the 'consequence' argument for the incompatibilism of determinism and free will / moral responsibility. In short, it says that if you are not responsible for X, then you are not responsible for the consequences of X. Applied to the present case: We aren't responsible for being born with various natural talents, therefore we're not responsible for the fruits of our talents.
This sort of reasoning might be appealed to in support of Roemer's 'equality of opportunity', according to which a retarded child must be able to become a rocket scientist just as easily (i.e. with the same degree of effort) as anyone else. (And so much the worse for rocket science, I suppose.)
This is just crazy. It's crazy in practical terms, of course. But it's also bad theory. After all, the inclination to expend effort is itself a natural character trait which has its origin outside of our control. Roemer partially concedes this, but assumes that we still have some control over our effort levels. He thus takes 'degress of effort' as being relative to the baseline for someone in our (genetic and environmental) "circumstances". A natural slacker who puts in some slight effort is held to be more deserving of reward than someone who is naturally hard-working.
But if he's allowed to say that we're responsible for our degree of effort, despite it being ultimately caused by events beyond our control (if determinism is true), then why not say the same of the fruits of our natural talents? Just because we did not choose our talents, it does not follow that we are not responsible for our use of them. At least, no compatibilist should be willing to grant such an inference.
People are just as responsible for the fruits of their talents as they are for the fruits of their effort. Both are character traits of the person, and there is no justification for treating them differently. We are responsible for both or for neither - take your pick.
I should clarify that my aim here is simply to argue against the notion that fairness, or giving people what they deserve, requires strict egalitarianism. Some might argue the extreme opposite: that people deserve what they earn, so taxation for redistributive purposes is wrong. I disagree with that position just as strongly.
Perhaps what I should do is deny desert altogether (or else, perhaps more plausibly, deny that market income reflects desert). You do not deserve your income, but nobody else deserves your income either! Everyone is on equal footing, so we should simply distribute resources in whatever way is best on independent grounds: Utilitarianism, in other words.