Not an issue per se. It shows the limit of the analogy used by defrost to justify such a world would be as functional as 1975’s was.

The basic assumption that the two situations are similar is just… false

Four billion is a goal that doesn't happen overnight, ergo it takes decades to get there during which time global education continues to improve and the application of automation to bulk resource handling increases.

Today, in my state, we extract and move more raw iron ore for steel production per year by a considerable factor more than the US ever achieved, and with far fewer people per tonne - largely due to better techniques and automation.

If you look about the world as it is you will realise that we are capable of having greater production and better lifestyles across the globe with a lower population and less by product from consumption than we do today.

The means and levels of consumption today are problematic to say the least.