Let's assume your example is true.
If they could get someone to do the job equally well for $400,000 a year, don't you think they would? The station management must think she is worth $600,000 or they would get rid of her. Don't you think they have a better handle on her worth than you do?
Sofia Vergara gets $40M/year. Seems obscene to me, but if they could get away with paying her $30M/year, don't you think they would. You can spit at economics all you want, insisting your value system is superior, and economics will win out every time. Save the spit.