> Looking at it with modern eyes, it would be easy to make said machinery operate like an amplifier of labor. Meaning that for each unit of labor used to operate the machine, the owner would get a multiple of said labor out.
I agree with this, but trying to look at the issue with Marx's eyes I think he saw the subject like this (I'm no Marxist, nor an economist, just making an educated guess): Of course that the machines help their owners (the capitalists) make more money in absolute terms (the amplifier of labor you mention), but at the end of the day what matters for a capitalist (and is one of the essences of capitalism, I think) is that he should make more money compared to the other capitalists.
Now, I think Marx says that all capitalists (as a class) can have access to the same machines -> they can all enjoy the same returns caused by said newer, better machines -> so technology/science progress is no differentiator in the long run between capitalists, because the new, better machines bring them the same rate of profits (of course a company or two can go bankrupt if they haven't modernized fast enough, but we're talking about more general stuff). What I think Marx is saying is that the main (and in his view the only one that counts) differentiator between capitalists consists in how well they can "squeeze" out labor out of the, well, labor-classes (industrial workers back in Marx's time). And if you look at the economic history of the past 25 years (give or take) you can see that the grand winner of this period, China, is actually a capitalist country (I'm ignoring its one-party rule thing) that knew pretty damn well how to squeeze out labor out of its citizens/workers, and also that the United States has had a better economic run compared to Europe also because it treats its workers worse (and unfortunately people over here in Europe have started noticing this and have started copying the US).
> From that he concluded that it would actually be in the best interest of industrial capital to collaborate with labor in a common front against finance, but that sadly they would side with finance capital until it was too late.
That sounds pretty interesting, I've never got to read his Capital II and III, I guess I'll give them a try.