> The limited supply is because natural resources (especially oil) are now competed for by a much larger percentage of the world (ie. higher demand).

Prices are higher because of high demand - i.e. inflation.

> There are certain fixed or constrained resources (land, etc) that more people are competing for today than ever before

That has been true for all of human history. Population has been growing.

What has also been true is that technological advances have easily kept ahead of this for all of human history.

> The world population has doubled (or more) since the glory days of the USA, if nothing else.

The world population is also a lot more productive.