

Physical access isn’t game over, it’s only game over to a determined hacker. The vast majority of people aren’t competent enough for it to be an issue. It’s just like how a determined thief can get through almost any lock or door, but it takes effort and time, and skill which many casuals just won’t have.
Full-disk encryption passwords are the most important password, they can prevent physical access from being game-over.
Unix was originally designed to be multi-user, so different passwords protect different users from each other.
Linux doesn’t have a UAC-without-passwords equivalent really, programs can interact with the Linux UAC equivalents just as much as you can, so the password makes sure it’s really you, and not a malicious program or person. UAC on Linux would require an almost fundamental architecture change, in a way contrary to most of how Linux is used now.
Did you really never use a password with Windows? That seems wild to me.








The idea of not having a password at all is just so foreign to me, did you at least use biometrics or something?
It seems like not having a password would make some UAC bypasses easier, too.