pixpot If we compare with a computer running Linux (or basically any other OS) you have the choice to login in to any of these on boot up without haveing to login as root or with sudo privileges first.
GrapheneOS is designed to be harder to break into than Linux etc. Google and then the GrapheneOS team started with the standard Linux model and added many features to protect data against tampering and disclosure.
So did Apple. If you boot a modern iOS or MacOS device, it comes up a little and then stops until an authorized user unlocks enough state for a complete boot.
Linux, especially as most often deployed, is not at all the pinnacle of security.