The problem with "savings" is that the everyday understanding of the term is "to hoard money." Hoarding money does not create investment, or accumulate capital. It merely enables you to lay claim to a larger share of whatever plant and labour exists when you move to spend the money.

I think the fallacy here is the idea that money always represents the same thing. It does not. Imagine: 1 million people are expropriated of their savings which they planned to use to buy a (imported) car and that capital accumulation is used to say, build a dam?

As a layman, it strikes me that you are being too theoretical. For me it depends on how capital accumulation is used. Politics can help there.

This may not seem like such a problem - after all, working 60 % of the time for 50 % of the goods isn't an atrocious deal. But during the time (a decade and a half or so) that plant is deteriorating, you'd have to work longer hours to obtain the same production (on average you'd have to work something like 1 % longer every year - minus any advances in total factor productivity)

My impression again is that you are over-theorizing (and over-simplifying). Interestingly I think the seeds of an answer are in your own words: "minus any advances in total factor productivity".

I would really like to continue this discussion, but this is above my paygrade and I do not have the time (the deadline to submit my PhD is looming)