Part of the problem is that increased demand for labor no longer scales with the demand for goods.
If demand for automobiles doubles, for example, you will have to pretty nearly double the number of workers to produce twice as many vehicles. But in an information-based economy where products are ethereal zeroes and ones, if demand for a piece of software doubles, you don't need to hire anywhere near twice as many people. You don't need any additional developers to "build" more units of the same software program; you may need a small number of additional sales and support staff but that's about it. Revenues can grow fivefold and barely require hiring at all.
So the real question, IMO, is: How do we adapt to the increased irrelevance of labor in today's economy?
I understand your concern about technology replacing some of the demand for labor but I wonder if the demand for labor has really gone down. I presume they have here in the U.S. starting with the steel mills, etc.
How do we get information on the number of labor hours that exist today..globally and compare it to 20 years ago. I think it's possible we might find labor hours have actually increased...just perhaps not here. So many of ours ...are not here anymore.
ummmm..might have to look into that...