My experience on this front leads me to the conclusion that salaries are not actually gauged to 'worth.'
If Rooney is on 12 Mil/annum, then based on the sort of cock ups that each can make, Hester is grossly underpaid!
Usually what happens is that people form a judgement as to their own 'worth' to a given organisation, then they see someone, who in their opinion is not 'worth' as much, receive a pay rise, they want one. Nothing to do with whether they need any extra, simply proof as to their own value.
Neither Rooney nor Hester are likely to live long enough to spend their money, if the top wack in their chosen professions was £100000/annum they would accept it, till the goal keeper got a rise or Hester's secretary got a rise, then they would want to maintain the differential.
Most Prime Ministers would probably do the job for free!
Roy.