99% of time time, my missing tools are AWOL because I used it, set it down, and just plain forgot where.
Yea, tools getting stolen are a huge drag.
I remember having a cordless sawzall and two benders sprout legs while I was doing underground for a restaurant. Concrete crew was the only others around. I asked their foreman if any of their guys had found them. "You think any of my greasers would admit stealing your tools!?!?" was his reply. I said, "I never said they stole them.... I asked if any of them
found them!"
Two weeks later, the shell was up and I told the carpenters to keep a close eye on their tools. Sure enough, the same 'crete crew was pouring the parking lot, and the carptenters scaffold they had set up inside went missing. Right in the middle of the day. Dozens of other trades around. Interesting, as the same 'crete crew was there.
Once they left the job, I never heard of anything else come up missing. Hmmmm.
Personally, if I see a tool laying somewhere, I leave it. If it's still there at the end of the day, I'll pick it up and try to find out who it belongs to.