Pinball is bigger than most think. There are owners who only see their games as commercial equipment and there are collectors who seem amazed that the first group still exists.
I've done rental jobs for two companies now. Its not that uncommon. People rent arcade equipment to entertain at events and a pin gets thrown in there, or we rent pins as props or promotional attractions, like a theater staging tommy for example.
I haven't seen any problems with customer abuse. Its not at all like routing pins, where the games are unattended, full of cash, and at the mercy of drunks and kids. The bad stuff that happens is in the bar corner when nobody's watching, not when its on display at some fancy event. For rentals, I'd be more worried about damaging the game moving it in and out of the event than customers damaging it.