I think the problem is that you're not explaining which country you're thinking of, and seem to be suggesting it's the same legal situation everywhere

The concept of needing to register copyright does not exist in most countries. In many countries you just have it and you can enforce it.

Fediverse servers do exist outside of the USA so this is relevant for people who run those servers.

That's only US courts. Other countries don't even have a procedure for registering copyrights.

No, there is no need to register copyright in Australia.

How about you read the very first sentence of my little snippet again.

The very first sentence.

The sentence that says, "You don’t need to register for copyright in Australia."

You know, the sentence that effectively describes what needs to happen if you're thinking about registering copyright in Australia.

Perhaps in your country you have to register works for copyright so that the courts will recognise your claims of infringement. Other countries, maybe not so much.