The observation in the first half of your comment seems sound but your explanation doesn't make sense.
There's rather a lot of land in the world outside of the US that could have a datacenter built on it. There's also a lot of Australia that's uninhabited but not uninhabitable.
I oversimplified a bit, by "land" I also meant associated infrastructure, which includes for example access to electricity. In most countries, building out new high-voltage infrastructure to where it does not exist is both financially expensive and technically painful (planning permission etc). Same for pulling fibre runs to the middle of nowhere.
No doubt other things like local laws, tax rebates and whatnot also come into play as well.
You may seek to argue that there are a small number of third-party datacentre sites where the cloud operator is the sole tenant of the building. But this again is not the same thing as the cloud operator building their own. They get the option to up sticks and leave at the end of their contract. They also don't have any responsibility over facilities management etc.
At most sites, the cloud operator simply has whole or part of a floor (or floors in larger buildings), the rest of the building is occupied by third-party customers.
There's rather a lot of land in the world outside of the US that could have a datacenter built on it. There's also a lot of Australia that's uninhabited but not uninhabitable.