By your "overly-greedy" conclusion, in your equation do you include the pressures of international competition that exist on an uneven playing field?
If your competitors can sell for lower costs than you due to the cost of living is not as high (likely the quality of life is not as high either) - because they don't take care of the population as much, don't have safeguards in place, etc), and 2) therefore the margins to be lower - and so if not competing with pricing from the uneven playing field - then the whole company may go under, or worse be taken over by states or companies essentially owned/controlled by totalitarian states?
If you extrapolate out that then means more and more power-money-control flows towards bad actors, propagating, compounding, and accelerating their takeover of potentially everything globally - so while in the short-term unions may maintain a certain quality of life, until totalitarians centrally control the means of production - and then everyone becomes slave labor, the ones who last will be those conditioned to comply and/or think whatever controlled-relatively low quality of life is normal and the only thing possible.
Also, the solution is the relatively free market to your conundrum, right? If it's "so easy" then the people who want to unionize for a certain maintained standard can then find investment and start their own company - and then they too can face the economic pressures of international competition on an uneven playing field, and they'll see how well they can fair too; and then cool if they can outcompete everyone and maintain their desired quality of work-life, but in their effort to aim for their goals they're far more likely to get a rude awakening of competitive market forces.
There's a reason there's a naturally formed hierarchy of competence, and highly competent people gravitate towards voluntarily wanting to be led and employed by the most highly competent people they can identify - who helps drive and support their passion by having a foundational trust or belief the company being led by whatever organizational structure (especially including founder(s)) has allowed them to reach their current state of success; and then an ideological mob of workers who apply pressure for improvements, where the business will want to keep good employees happy - presumably they'll be more reasonable than not in work load, work conditions, etc, in part as keeping trained employees is far cheaper and more efficient than hiring new - if they can match the requirements the company has set for the system, if the system appears to be functional-fluid and efficient for the majority - the majority ideally highly competent-healthy individuals who are gauged as accurately as possible to being happy enough with their income and conditions, then that is arguably the best way to orient and determine course corrections if/when necessary.
And then we haven't even begun the conversation of when Tesla Bot et al will be able to replace more and more tasks - to begin the discussion of how then how do we safeguard against tyrants from capturing and deploying these systems against humanity and creating a Terminator-like future?
It seems Elon has thought-extrapolated this far out, and why he's concerned with AI - and why he also believes UBI is likely inevitable; UBI which can be weaponized by bad actors as well, e.g. if you have everyone getting enough money to survive then boredom and cults will be easy to form, who can then be weaponized against the very system they now depend on; why education and understanding the fundamental mechanics and policy that allows for whatever thriving society we design and follow next, tapping into the abundance of the universe as soon as possible - and forming Heaven on Earth, thy will be done on Earth as it is in Heaven.