This shows what they failed to consider in those optimistic views of the 1930s like John Maynard Keynes who predicted that his grandkids would work just 15 hours a week.
Slaves don't trade productivity for their lives, they trade time.
No matter how many trillions of times more productive human activities will become, slaves's time will still belong to the masters and very little of their life will belong to them.
So using the "wage slave" rethoric is punished now by the Thought Police. Happy happy thoughts and be greatful for the opportunity to trade our lives for a measly pay working for the man.
"Slavery" is a powerful word, understood universally, with high chances of proving the point and making an impact when used.
Your censorship of it's usage may have been done on good intentions but the results are nefarious.
Does it seem to you that we are living in some Nirvana / restored Heaven Of Humanity? Take a look at this, wage slavery makes 25% of work classification: https://www.nirandfar.com/wage-slaves/
Confining the word "slave" to some well-in-the-past primitive dawn of humanity and punishing us for using it to depict the deplorable state of humanity today does nothing for improving said state and makes you in the best case one of the "useful idiots" of the establishment ( https://en.wikipedia.org/wiki/Useful_idiot ).
How do you define a "slave"? Think of this definition: "a slave is any person that trades their time in exchange for the right to live". Does it seem to you that Elon Musk is a slave? How bout someone working on a computer 1,000,000 times more powerful than 30 years ago and going through even more drudgery with less stability and guarantee of making a living out of the productivity increase?
Is it really the best that civilization can throw at the versatility and capability of the human mind? Fixing bugs in the 100'th million line of crap framework code and the perspective of being replaced by a statistical model? That's your glorious "non slavery" world you censor from using?
Slaves don't trade productivity for their lives, they trade time.
No matter how many trillions of times more productive human activities will become, slaves's time will still belong to the masters and very little of their life will belong to them.