"Do this or starve" is the default position of all forms of life.
Sure. Fortunately, us humans and our big brains can move things away from those "nasty, brutish and short" defaults. Infections used to mean death or amputation, now you take some pills. It used to take months on a dangerous voyage to go to another continent, now you can do it in comfort, safety, and less than a day. We've made many things better than what "the universe" handed out.
Such a guarantee is impossible.
It always astonishes me that people call things which are currently being done "impossible". Many countries in Europe, for example, do exactly this. Something is by definition possible if it has in fact happened.
There is no "one side". There are millions of employers and millions of workers.
While this is true, that does not mean that the employers do not hold disproportionate power in that relationship.
If you see all possible employers as just "one side" which is out to get you ... chances are you're pretty much unemployable.
If you want to make it about me, I do just fine as a contractor. But I actually am legitimately one. Someone will tell me "I want a (website made|database fixed|application written), and here's what I want for it", and then leave me to figure out all the details. If, on the other hand, they expected me to display their logo on my car, and things like that, I would be an employee, not a contractor.
The biggest problem during the Gilded Age wasn't abusive employers, it was uncontrolled immigration.
That is patently false. Look up the Colorado Coalfield War for an example. That wasn't people who had immigrants take over their jobs; it was people who had jobs and were severely mistreated by their employers. And they couldn't just go get another job, because all the employers pulled the same things! The US wanted immigrants at that time; a tremendous amount of manual labor needed done and they couldn't let them in fast enough to fill the need.