We had a rash of losses last year. Maybe I'm stingy; I'm surprised how cavalier people are about it. "Oh, it's somewhere between 2 and 3." The best was when a guy hoped we'd look for it for him, on one of the greenest legs of the year. "Um, no thanks." Anyways, hopefully this results in fewer "$40 please"s.
After temporary losses of either my glasses, compass or SI during the past few years, I often put small pieces of flagging tape on both. Simultaneous failure of both the leash and finger elastic is pretty unlikely so leashing is a good thing. That said, I have had the leash catch on honeysuckle, flinging my SI into the woods. The tape makes it more visible in the leaves.
Elastic leashes make for longer flings
We use leashes on all of our rental cards. The guy (not Guy) lost it anyway.