[Hermitian909]

Line managers basically never have the final word on pay, at most they sometimes get discretion to move pay around within a defined band. Pay bands are handled by the C-suite in small companies and compensation departments in large companies. Both generally reference databases of "market rate" compensation.

As a rule, people are not paid "what they are worth", they are either paid market rates or convince the company they have a differentiated skillset that warrants compensation beyond what is normal in the market (usually by tying their performance to some important metric). No one has yet found a way to change this from within a corporate structure.