In many cases, employees are replaceable cogs who can be done without for the brief period before being replaced, while employment is vital and the absence of it for even short durations can be life-threatening.

Software is a rare exception, not the rule. Even then, people like me who have enough savings to live for over a year without a paid job (looking after a parent with Alzheimer’s in my case) are a tiny minority.

Employers have a much larger pool from which to choose employees than the pool of employers from which any one employee may choose.

In addition, the majority of employers have (either by coincidence or agreement) landed on a similar set of crappy and unreasonable contracts. For the vast number of employees out there, it's either submit to the contract or remain unemployed.

If you have the money/family support... If you are young enough... If you are not a woman... Add any minority to the list as needed. You can't always afford to turn down a job offer.

Power is not measured by your ability to walk away from a deal, but by your next best alternative if you do walk away.

Lets not pretend like every deal not made at gunpoint was some how made by parties of equal power.

Because if you can't buy food and shelter, YOU DIE. The company's worries are less severe.

Yes. But that’s not the point. The point is that the leverage of both parties entering the negotiation is in most cases very skewed.

Because they absolutely do. A company that loses an employee likely isn't going to suffer. A person that loses or cannot get a job absolutely is.

"Contracts only happen by mutual consent."

That's not true in the least. When your alternative is to starve, one cannot really call that "mutual consent".