In other words, local account security is basically non-existent on OS X. Well, that's useful information for anyone who might be thinking about deploying Macs, I guess.
No - not at all. In a multi-user system (i.e. schools) a competent admin wouldn't LET the kids have access to Terminal or similar utilities - they would be removed from the common apps folder (accessible to all) and kept in the admin's private folder (access denied to regular users).
I manage a small LIMS system at work and I've relocated all the 'toys' to secure folders so that the common users can't f!-up anything. AND, they can't just install anything they want without an admin's permission.
Do you have little kids? Would you leave knives in the cutlery drawer? Would you leave the outlets uncapped and leave paperclips lying around? Would you leave matches lying around?
Would you open-up r/w/d privs on all files to everyone on your system?
This kid not only left the front door open for the thieves; he took the lock out of the door.