Even more of a problem if they borrow a tool out of your bag without asking first. And I'm not even talking about thieves, just guys that weren't taught right.
Well that's just it, and a lot of people forget (or never head of) the Golden Rule. (And I'll loan you that tool, but put it back
in my hand. Not in my bag, not next to my lunchbox,
in my hand.)
Kind of in the personal-use department-
The office had a postage meter, unlocked and always ready to use. Same for the copier. The rule was that if you needed to mail something, just write that down in the book to account for it. Pretty much every one did because anything under a dollar or two was conveniently forgotten by the office manager. OTOH if you wanted to do a larger mailing, just give her a check for the postage you used and all is good. Same for the copier- a couple of pages is fine, past that bring your own paper. It all worked out.