Full Idea
Without inequalities, people will have no incentive to do one job rather than another - to do the kind of work which is most useful.
Gist of Idea
Inequalities are needed, as incentives to do the most important jobs
Source
Adam Swift (Political Philosophy (3rd ed) [2014], 1 'Rawls')
A Reaction
The reality is that the lowest pay goes to the jobs that no one wants to do, and all the really nice jobs are usually well paid. Which is a conspiracy, because all the salaries are set by the people with the nice jobs.
Book Reference
Swift,Adam: 'Political Philosophy (3rd edn)' [Polity 2014], p.28