Finding a new job takes a lot of energy. People give you raises to prevent you from being bitter enough to spend that energy. They also know that regardless of

Finding a new job takes a lot of energy. People give you raises to prevent you from being bitter enough to spend that energy. They also know that regardless of what they pay you, you will eventually quit anyways (unless they start paying you in the top 10% of the field, but then, what's in it for them at that point). So no, 30-40% salary raises do not exist. At the executive level they sorta do, in the form of options and bonuses.