From adopting the moving assembly line to mechanisation and automation in the production process, far less labour can produce far larger quantities and more tech-heavy vehicles than when they were first invented.

After the moving assembly line's adoption, but well before full mechanisation, in 1930 economist John Maynard Keynes predicted that we'd see a point of efficiency - across most industries - where much of the population would only need to work 15 hours a week to meet their needs.

What ever happened to that? I believe it has been a combination of things.

The short answer is we feel we need a lot more than we did then, and it all costs more. We also seem to need much higher levels of education (also costing a lot more). Plus most of us will live longer, meaning longer retirement.

We're all competing for limited resources (a major cause of inflation), and many of the benefits of efficiency went to entities other than the individual worker (plus inflationary periods seem to make the wealthy wealthier).

It's easy to observe that within many goods industries the benefits of efficiency and mechanisation appear to have gone up the hierarchy, not down, with owners and shareholders getting richer rather than workers needing to do fewer hours. But many more products are available now too, and we're consuming them.

Many economies have also shifted (or to some minds, graduated) to having more workers in the services sector rather than agriculture, mining or manufacturing.

In Australia for instance, almost 90 per cent of the workforce is now in one of the service sectors. Again, technology has made many of these jobs more efficient, but other jobs have emerged especially in the gig economy like delivery drivers serving individual demands with each journey such as food for a single hot meal. Services like that can only become so efficient (they can only take so many orders per journey). And the pay continues to be comparatively low already so fewer hours just isn't a realistic goal.

The high demand for such services (including from those crying poor) also circles us back to that point about what we think we need. The level of technology, comfort, and services available to ordinary people has increased beyond the imagination of probably the brightest minds of anyone in the 1930s (even Dick Tracy's 2-way wrist radio didn't make its first appearance until 1946).

Some home appliances for instance are well worth the investment because of the time or money they save us, like washing machines and fridges. Various other shiny things, not so much. In other words, part of the reason is the everyday consumerism that we seemingly can't resist, whether it's for mere convenience or the perception of status various flashy things might bring.

Then there's the ever-escalating cost of housing, whether you're buying or renting. Keynes' prediction did not seem to anticipate that cost spiralling out of control the way it has done in certain countries (depending on their housing policies).

In Australia, with long-existing tax laws encouraging investment properties to partly substitute (or completely be) nest eggs for retirement, it's ended up causing competition among those who can afford it, further driving up the cost of rent and keeping many of the younger generations out of the buying market entirely.

Meanwhile only some of the population have taken the opportunity to move somewhere cheaper. The rest continue to compete for the limited availability around the major cities, for reasons that include the availability of work and the proximity to friends and family. That said, many homes aren't as modest as they were in the 1930s either.

On the subject of retirement though, life expectancy is now much longer than it was in the 1930s (albeit distorted by the high number of infant deaths back then), so even if you decided to live more modestly during your working years you'd be silly not to prepare yourself for a long retirement.