Notepad is a very basic editor. Likewise, most Linux distros come with nano or some other very feature-limited editor.
While I did once know a developer who used notepad as his primary editor, it was never intended to be anything but a very simple editor for INI files and the like.
Yeah, I think it's safe to say most Linux and macOS systems don't have an editor as basic as Notepad (even ed has regex support!) The closest equivalent I can think of is Mousepad from Xfce. I don't really see the need for it either. If your distro comes with something like nano, gedit or KWrite out of the box, why would you need something like Notepad?
While I did once know a developer who used notepad as his primary editor, it was never intended to be anything but a very simple editor for INI files and the like.