[JamesP81]

Actually it is. If you don’t believe it, don’t do it and just use the OS

No, sorry. A Windows computer has the OS pre-installed. At the factory they do a full install in a special mode of operation (I can't remember the term offhand) where they preinstall the OS and whatever software comes from the factory with the system, without doing any of the customizations you'd do at first boot.

The stuff you do at first boot is just configuration on an already installed OS. You can tell by how you can get through that stuff in a couple of minutes. A real, full dress OS installation would take way longer (SSDs have cut this time down a good bit).

[AppyPappy]

Windows 10 is pre-loaded on a machine. The configuring is part of the install.
We have truly *pre-installed* Unix VM’s. All you do it bring them up and start working. You don’t have to do anything to make them work.