[bombcar]

There's also this insane (or amazing) drive towards productivity that we don't notice - we build roads that not only support 80+ MPH 18 wheelers, but do so durably and safely!

You can build a road an 18 wheeler can transit with manual labor, just slowly. And if you don't need to support more than a Jeep, the road can almost build itself.

Or another way - building a modern house with modern conveniences and efficiencies is pretty dependent on a ton of things.

Building a sufficient house in many parts of the world is dependent on manpower.

[defrost]

Being W.Australia, where the Pintupi Nine popped into the modern world during the 1980s, there are a few people happily getting along with no house at all, as they and their families ever did for a few thousand years past.

But on that matter of road building, here's a vague relative kitted up to travel and take photo's in 1920 or so: https://live-production.wcms.abc-cdn.net.au/1d5472eb9b8a4e3e...

and here's one of his images taken much the same time of a road and railway being built: https://live-production.wcms.abc-cdn.net.au/20d3070e95eb924a...

It's all manpower and horse drays - the really tough bits are dropping, chopping, and moving those trees, they're a bit bigger and tougher than they look.

[bombcar]

We're also very likely to get a "technology flyover" situation - in the past, if Caesar wanted to send something (even just a message) fast to the edge of the Empire, he needed a road the entire way.

If Lincoln wanted troops moved to the front, he needed rails, or lots of roads and time.

Now we can travel and communicate between vastly distant areas without intervening connections - you just need an airport in Perth and something resembling a landing strip in the Outback, and you have travel. Satellites and radio preclude the need for wires to be run.

If humans do go extinct, it's going to be from a lack of will rather than a lack of means.