I'm sorry, I'm not sure I understand what your trying to say here.

First, of course not many people live in the desert.

It's a fucking desert! And we have a massive coastline to live on instead.

But your second point is where I'm confused.

Are you comparing the part of Australia below the tropic of Capricorn with Brazil closest point to the equator.

Bit disingenuous don't you think.

And before you try to say but everyone in Australia live below the tropic of Capricorn. No we don't.

Our largest city's below it, sure. But plenty of people still live in that area.