> I'll happily send you my signing bonuses if you send me your salary.
You've conceded it does have value to you, as you want something in return.
> If you want to talk meaningfully
I'm afraid it's not up to you to define meaningfully. People in a free market are paid according to the value they produce, not some average of what other people produce. Anyone paid less than that is in a stronger negotiating position than one who is paid more than that.
If you feel you are underpaid, take a good hard look at what value you are bringing to the business. If that's looking good, take that to your boss, show the evidence, and negotiate for a raise.
> You've conceded it does have value to you, as you want something in return.
A signing bonus is significantly less valuable than salary; that signing bonuses are substituting for salary increases is a sign that employees are losing leverage in negotiations, i.e. the complete opposite of what you originally claimed.
> People in a free market are paid according to the value they produce
Indeed, and thus the fact that the labour income share is so much lower than it was 30-40 years ago is an indication that the current market is deeply distorted (e.g. by the famous "anti-poaching agreement", and no doubt more recent equivalents).
> A signing bonus is significantly less valuable than salary
That depends on their relative magnitudes. Nevertheless, signing bonuses means workers have negotiating power.
> labour income share
Let's say you and Bob work for Evil Corp. Bob gets replaced by a robot that is twice as productive as Bob was. Your job hasn't changed. The overall productivity of Evil Corp has gone up because of the robot.
The robot makers and investors get the income share from the increased productivity of the robot.
> Nevertheless, signing bonuses means workers have negotiating power.
Maybe they mean workers have nonzero negotiating power. But they don't mean that workers have more negotiating power than in the past.
> The robot makers and investors get the income share from the increased productivity of the robot.
If that income share went to the workers who made the robot, it would show up in the labour income share and the overall labour income share would stay high. (But what actually tends to happen is it gets captured by a rentier instead).
You've conceded it does have value to you, as you want something in return.
> If you want to talk meaningfully
I'm afraid it's not up to you to define meaningfully. People in a free market are paid according to the value they produce, not some average of what other people produce. Anyone paid less than that is in a stronger negotiating position than one who is paid more than that.
If you feel you are underpaid, take a good hard look at what value you are bringing to the business. If that's looking good, take that to your boss, show the evidence, and negotiate for a raise.