For extremely limited values of 'everywhere' which shake its definition.
I don't think a basic Arch Linux installation includes perl. Windows as you say would surprise me. 'the major Linux distributions' (plus I think macOS, perhaps inherited from BSD, no idea) might be fair, but certainly not 'everywhere'.
To my mild dismay, it's not part of the base system in FreeBSD anymore[1]. It is easily installed, of course, but that means #!/usr/bin/perl does not work without manually creating a link.
[1] I think it used to be part of the base system, at least.
And this was the right move. It meant that the version of Perl was decoupled from FreeBSD releases, allowed you to choose which version to install, and allowed you to install multiple versions if needed.
For some values of "everywhere". Pretty sure this is not true on Windows, for example.