- The default user created at setup of OSX is in the admin group.
- Certainly the 'has run sudo' is a bit of a restriction, but even running something like the Homebrew install script runs sudo. (Maybe 'users that run Homebrew without understanding sudo' is an even smaller restriction, but a few members of my research group live in exactly this intersection!)
- Do you habitually read every line of source code your computer would execute before you run that code?
And yes, I very seldom run scripts copied from somebody else so when I do, I make sure I know what is being run. Granted, I'm a Linux and Windows user so the OSX philosophy might be different.
The main homebrew page says, 'run this ruby script'.
The ruby script is available at: https://raw.github.com/mxcl/homebrew/go
The script includes a sudo command.
To be fair, I hadn't read the script in detail when I wrote my post, just far enough to see there was a definition of a sudo function. On review, it looks like they either call it to chmod/chgrp HOMEBREW_PREFIX (sometimes), or run sudo to create the directories.