The boss has the power to terminate your employment relationship. You have the same power. If you are in software, most likely you'll find a new job long before they find a replacement. That's certainly true of my team.
What "power" do you believe the boss has that an employee doesn't?
The boss can usually harm the subordinate's quality of life much more than the subordinate can harm the boss's quality of life. If you are fired than you immediately have less income. Your reputation is damaged if people learn of it. If you quit then it rarely causes any harm to the boss. They still have the same income. They probably have several other subordinates. Power imbalance is the defining characteristic of the boss/subordinate relationship. The boss can give orders and the subordinate will obey because the consequences if they refuse are worse for them than for the boss. This is what you pay to gain the stability of employment.
If I or most of my colleagues are fired we'll have less income for a month or two. Our lifestyle won't change [1] unless we want it to. In contrast, if my employees quit, my projects are significantly slowed, I need to spend a lot of effort hiring new ones (I hate hiring) and I'll look bad.
Furthermore, insofar as costs are unequal, that's merely a reflection of the principal/agent problem. Similarly, as a boss (but not an owner), I'm also motivated to overpay my workers; it keeps them happy and helps me get my work done (by hiring better people), and it's not my money that I'm spending.
[1] My colleagues all live in a country with a 30% savings rate and where American levels of financial recklessness are not socially acceptable.
So you choosing to leave is the same as being forced to leave? A boss has power you do not in many ways. They can increase your pay, they can choose the projects you work on and do not work on, they can terminate your employment whether you want it to terminate or not.
Choosing to leave is equivalent to being fired; either my boss or I can unilaterally terminate my employment agreement.
My boss can increase/decrease my pay, and I can either accept or reject the new agreement. I can also demand higher pay or threaten to quit. They can tell me to work on certain projects or I'm fired, I can say I want to work on certain projects or I quit. They can terminate my employment whether I want to or not, I can quit whether they want me to or not.
Employment is a market; a situation characterized by cooperation and mutual agreement. You may choose to pretend you have no agency and are a mere victim to your boss, but I do not. My employees don't pretend this either, which is why I need to keep them happy.
I wonder if it's not in fact that he only has as much power as you yourself give him. Then pretending that he has no power, actually makes it so that he does not have any power over you.
"They can tell you what to do, and how to do it. And if you don't, they can fire you. And when you have no job, you have problems eating, a place to stay, and a much harder time getting jobs."
