That's just the way it works. There's numerous alternative arrangements and arguments in favour and against.

You could think about if the owner of a business generously decides to give all his employees a pay rise - the government now receives less money because the employees pay a lower marginal tax rate than what the owner would have paid if he kept the money for his own higher salary. Should the government get involved here and claw back that lost tax?

Why should the state get any of it, regardless of what I spend it on?