Will, I've asked that question of fairness many times. The only solution is a Union. Just talking about it will get you in hot water with management. Without a union, it's dog eat dog. Whoever argues and carries on will get more money. Whoever socializes with management gets the best deals. HR will be of no help whatsoever, as managers stick together. New tech hires from head hunters come in on first day and spend it talking on their second phone " yeah, i have second job, it was part of my hiring" then act like they own the place.
Then see sales people get shafted by some cunning rep who seems to control a huge territory, shutting out all others, by being the social butterfly with management. It works, yes a university study proves it....kissing tail really helps!
If you want better, talk to those head hunters, get your best deal, ask for more vacation. But know where your going and what you will be doing! If you get a great offer, then talk to those sweethearts again at HR, maybe they will deal now. If not, walk away to a new place